diff --git a/ebook_converter/css_selectors/ordered_set.py b/ebook_converter/css_selectors/ordered_set.py
index c68418d..c85b456 100644
--- a/ebook_converter/css_selectors/ordered_set.py
+++ b/ebook_converter/css_selectors/ordered_set.py
@@ -1,7 +1,5 @@
 import collections
 
-from ebook_converter.polyglot.builtins import string_or_bytes
-
 
 __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
@@ -18,7 +16,7 @@ def is_iterable(obj):
     Strings, however, should be considered as atomic values to look up, not
     iterables.
     """
-    return hasattr(obj, '__iter__') and not isinstance(obj, string_or_bytes)
+    return hasattr(obj, '__iter__') and not isinstance(obj, (str, bytes))
 
 
 class OrderedSet(collections.MutableSet):
diff --git a/ebook_converter/customize/zipplugin.py b/ebook_converter/customize/zipplugin.py
index 4113c4a..9f129e7 100644
--- a/ebook_converter/customize/zipplugin.py
+++ b/ebook_converter/customize/zipplugin.py
@@ -11,8 +11,7 @@ from ebook_converter import as_unicode
 from ebook_converter.constants import ispy3
 from ebook_converter.customize import (Plugin, numeric_version, platform,
         InvalidPlugin, PluginNotFound)
-from ebook_converter.polyglot.builtins import (itervalues, string_or_bytes,
-        reload)
+from ebook_converter.polyglot.builtins import itervalues, reload
 
 
 __license__ = 'GPL v3'
@@ -33,7 +32,7 @@ def get_resources(zfp, name_or_list_of_names):
                 be just the bytes of the resource or None if it wasn't found.
     '''
     names = name_or_list_of_names
-    if isinstance(names, string_or_bytes):
+    if isinstance(names, (str, bytes)):
         names = [names]
     ans = {}
     with zipfile.ZipFile(zfp) as zf:
@@ -64,11 +63,11 @@ def get_icons(zfp, name_or_list_of_names):
     from PyQt5.Qt import QIcon, QPixmap
     names = name_or_list_of_names
     ans = get_resources(zfp, names)
-    if isinstance(names, string_or_bytes):
+    if isinstance(names, (str, bytes)):
         names = [names]
     if ans is None:
         ans = {}
-    if isinstance(ans, string_or_bytes):
+    if isinstance(ans, (str, bytes)):
         ans = dict([(names[0], ans)])
 
     ians = {}
diff --git a/ebook_converter/ebooks/conversion/plumber.py b/ebook_converter/ebooks/conversion/plumber.py
index c78145c..f97b5cf 100644
--- a/ebook_converter/ebooks/conversion/plumber.py
+++ b/ebook_converter/ebooks/conversion/plumber.py
@@ -13,7 +13,6 @@ from ebook_converter.utils.zipfile import ZipFile
 from ebook_converter import (extract, walk, isbytestring, filesystem_encoding,
         get_types_map)
 from ebook_converter.constants import __version__
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL 3'
@@ -1023,7 +1022,7 @@ OptionRecommendation(name='search_replace',
 
     def dump_input(self, ret, output_dir):
         out_dir = os.path.join(self.opts.debug_pipeline, 'input')
-        if isinstance(ret, string_or_bytes):
+        if isinstance(ret, (str, bytes)):
             shutil.copytree(output_dir, out_dir)
         else:
             if not os.path.exists(out_dir):
@@ -1216,7 +1215,7 @@ OptionRecommendation(name='search_replace',
         transform_css_rules = ()
         if self.opts.transform_css_rules:
             transform_css_rules = self.opts.transform_css_rules
-            if isinstance(transform_css_rules, string_or_bytes):
+            if isinstance(transform_css_rules, (str, bytes)):
                 transform_css_rules = json.loads(transform_css_rules)
         flattener = CSSFlattener(fbase=fbase, fkey=fkey,
                 lineh=line_height,
diff --git a/ebook_converter/ebooks/covers.py b/ebook_converter/ebooks/covers.py
index 8de7cd2..6794bb8 100644
--- a/ebook_converter/ebooks/covers.py
+++ b/ebook_converter/ebooks/covers.py
@@ -2,7 +2,7 @@ import re, random, unicodedata, numbers
 from collections import namedtuple
 from contextlib import contextmanager
 from math import ceil, sqrt, cos, sin, atan2
-from ebook_converter.polyglot.builtins import iteritems, itervalues, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems, itervalues
 from itertools import chain
 
 from PyQt5.Qt import (
@@ -270,7 +270,7 @@ def format_fields(mi, prefs):
 
 @contextmanager
 def preserve_fields(obj, fields):
-    if isinstance(fields, string_or_bytes):
+    if isinstance(fields, (str, bytes)):
         fields = fields.split()
     null = object()
     mem = {f:getattr(obj, f, null) for f in fields}
diff --git a/ebook_converter/ebooks/docx/writer/from_html.py b/ebook_converter/ebooks/docx/writer/from_html.py
index b9f03a7..c9894a5 100644
--- a/ebook_converter/ebooks/docx/writer/from_html.py
+++ b/ebook_converter/ebooks/docx/writer/from_html.py
@@ -11,7 +11,6 @@ from ebook_converter.ebooks.docx.writer.lists import ListsManager
 from ebook_converter.ebooks.oeb.stylizer import Stylizer as Sz, Style as St
 from ebook_converter.ebooks.oeb.base import XPath, barename
 from ebook_converter.utils.localization import lang_as_iso639_1
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL v3'
@@ -527,7 +526,7 @@ class Convert(object):
                     self.add_block_tag(tagname, html_tag, tag_style, stylizer, float_spec=float_spec)
 
             for child in html_tag.iterchildren():
-                if isinstance(getattr(child, 'tag', None), string_or_bytes):
+                if isinstance(getattr(child, 'tag', None), (str, bytes)):
                     self.process_tag(child, stylizer, float_spec=float_spec)
                 else:  # Comment/PI/etc.
                     tail = getattr(child, 'tail', None)
diff --git a/ebook_converter/ebooks/fb2/fb2ml.py b/ebook_converter/ebooks/fb2/fb2ml.py
index 540c603..f8b718c 100644
--- a/ebook_converter/ebooks/fb2/fb2ml.py
+++ b/ebook_converter/ebooks/fb2/fb2ml.py
@@ -15,7 +15,6 @@ from ebook_converter.utils.localization import lang_as_iso639_1
 from ebook_converter.utils.xml_parse import safe_xml_fromstring
 from ebook_converter.utils.img import save_cover_data_to
 from ebook_converter.ebooks.oeb.base import urlnormalize
-from ebook_converter.polyglot.builtins import string_or_bytes
 from ebook_converter.polyglot.binary import as_base64_unicode
 
 
@@ -408,9 +407,9 @@ class FB2MLizer(object):
         elem = elem_tree
 
         # Ensure what we are converting is not a string and that the fist tag is part of the XHTML namespace.
-        if not isinstance(elem_tree.tag, string_or_bytes) or namespace(elem_tree.tag) != XHTML_NS:
+        if not isinstance(elem_tree.tag, (str, bytes)) or namespace(elem_tree.tag) != XHTML_NS:
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) == XHTML_NS \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) == XHTML_NS \
                     and elem.tail:
                 return [elem.tail]
             return []
diff --git a/ebook_converter/ebooks/htmlz/oeb2html.py b/ebook_converter/ebooks/htmlz/oeb2html.py
index dacc03f..6d95b4b 100644
--- a/ebook_converter/ebooks/htmlz/oeb2html.py
+++ b/ebook_converter/ebooks/htmlz/oeb2html.py
@@ -13,7 +13,7 @@ from ebook_converter.ebooks.oeb.base import (
     XHTML, XHTML_NS, SVG_NS, barename, namespace, OEB_IMAGES, XLINK, rewrite_links, urlnormalize)
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
 from ebook_converter.utils.logging import default_log
-from ebook_converter.polyglot.builtins import string_or_bytes, as_bytes
+from ebook_converter.polyglot.builtins import as_bytes
 
 
 __license__ = 'GPL 3'
@@ -94,7 +94,7 @@ class OEB2HTML(object):
                 for el in root.iter():
                     attribs = el.attrib
                     try:
-                        if not isinstance(el.tag, string_or_bytes):
+                        if not isinstance(el.tag, (str, bytes)):
                             continue
                     except:
                         continue
@@ -155,10 +155,10 @@ class OEB2HTMLNoCSSizer(OEB2HTML):
         '''
 
         # We can only processes tags. If there isn't a tag return any text.
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
@@ -244,10 +244,10 @@ class OEB2HTMLInlineCSSizer(OEB2HTML):
         '''
 
         # We can only processes tags. If there isn't a tag return any text.
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
@@ -347,10 +347,10 @@ class OEB2HTMLClassCSSizer(OEB2HTML):
         '''
 
         # We can only processes tags. If there isn't a tag return any text.
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) not in (XHTML_NS, SVG_NS):
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) in (XHTML_NS, SVG_NS) \
                     and elem.tail:
                 return [elem.tail]
             return ['']
diff --git a/ebook_converter/ebooks/lrf/html/convert_from.py b/ebook_converter/ebooks/lrf/html/convert_from.py
index 5285c75..26f5f02 100644
--- a/ebook_converter/ebooks/lrf/html/convert_from.py
+++ b/ebook_converter/ebooks/lrf/html/convert_from.py
@@ -37,7 +37,7 @@ from ebook_converter.ebooks.lrf.pylrs.pylrs import (
     RuledLine, Span, Sub, Sup, TextBlock
 )
 from ebook_converter.ptempfile import PersistentTemporaryFile
-from ebook_converter.polyglot.builtins import getcwd, itervalues, string_or_bytes
+from ebook_converter.polyglot.builtins import getcwd, itervalues
 from ebook_converter.polyglot.urllib import unquote
 
 from PIL import Image as PILImage
@@ -1118,7 +1118,7 @@ class HTMLConverter(object):
             ans['sidemargin'] = int((factor*int(self.current_block.blockStyle.attrs['blockwidth'])) / 2)
 
         for prop in ('topskip', 'footskip', 'sidemargin'):
-            if isinstance(ans[prop], string_or_bytes):
+            if isinstance(ans[prop], (str, bytes)):
                 ans[prop] = int(ans[prop])
             if ans[prop] < 0:
                 ans[prop] = 0
diff --git a/ebook_converter/ebooks/lrf/html/table.py b/ebook_converter/ebooks/lrf/html/table.py
index a698f50..ca41acc 100644
--- a/ebook_converter/ebooks/lrf/html/table.py
+++ b/ebook_converter/ebooks/lrf/html/table.py
@@ -4,7 +4,7 @@ from ebook_converter.ebooks.lrf.fonts import get_font
 from ebook_converter.ebooks.lrf.pylrs.pylrs import TextBlock, Text, CR, Span, \
                                              CharButton, Plot, Paragraph, \
                                              LrsTextTag
-from ebook_converter.polyglot.builtins import string_or_bytes, native_string_type
+from ebook_converter.polyglot.builtins import native_string_type
 
 
 __license__ = 'GPL v3'
@@ -40,7 +40,7 @@ def tokens(tb):
             yield 2, None
         elif isinstance(x, Text):
             yield x.text, cattrs(attrs, {})
-        elif isinstance(x, string_or_bytes):
+        elif isinstance(x, (str, bytes)):
             yield x, cattrs(attrs, {})
         elif isinstance(x, (CharButton, LrsTextTag)):
             if x.contents:
diff --git a/ebook_converter/ebooks/lrf/pylrs/elements.py b/ebook_converter/ebooks/lrf/pylrs/elements.py
index 531d9cc..7da08e7 100644
--- a/ebook_converter/ebooks/lrf/pylrs/elements.py
+++ b/ebook_converter/ebooks/lrf/pylrs/elements.py
@@ -1,7 +1,6 @@
 """
 elements.py -- replacements and helpers for ElementTree
 """
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 class ElementWriter(object):
@@ -25,7 +24,7 @@ class ElementWriter(object):
 
     def _writeAttribute(self, f, name, value):
         f.write(' %s="' % str(name))
-        if not isinstance(value, string_or_bytes):
+        if not isinstance(value, (str, bytes)):
             value = str(value)
         value = self._encodeCdata(value)
         value = value.replace('"', '&quot;')
diff --git a/ebook_converter/ebooks/lrf/pylrs/pylrf.py b/ebook_converter/ebooks/lrf/pylrs/pylrf.py
index 9ff904b..7b78ae9 100644
--- a/ebook_converter/ebooks/lrf/pylrs/pylrf.py
+++ b/ebook_converter/ebooks/lrf/pylrs/pylrf.py
@@ -9,7 +9,7 @@ import codecs
 import os
 
 from .pylrfopt import tagListOptimizer
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems
 
 PYLRF_VERSION = "1.0"
 
@@ -397,7 +397,7 @@ class LrfTag(object):
         for f in self.format:
             if isinstance(f, dict):
                 p = f[p]
-            elif isinstance(f, string_or_bytes):
+            elif isinstance(f, (str, bytes)):
                 if isinstance(p, tuple):
                     writeString(lrf, struct.pack(f, *p))
                 else:
diff --git a/ebook_converter/ebooks/lrf/pylrs/pylrs.py b/ebook_converter/ebooks/lrf/pylrs/pylrs.py
index ccc71cf..96c07bd 100644
--- a/ebook_converter/ebooks/lrf/pylrs/pylrs.py
+++ b/ebook_converter/ebooks/lrf/pylrs/pylrs.py
@@ -51,7 +51,7 @@ DEFAULT_GENREADING      = "fs"          # default is yes to both lrf and lrs
 
 from ebook_converter import __appname__, __version__
 from ebook_converter import entity_to_unicode
-from ebook_converter.polyglot.builtins import string_or_bytes, iteritems, native_string_type
+from ebook_converter.polyglot.builtins import iteritems, native_string_type
 
 
 class LrsError(Exception):
@@ -90,7 +90,7 @@ def ElementWithReading(tag, text, reading=False):
 
     if text is None:
         readingText = ""
-    elif isinstance(text, string_or_bytes):
+    elif isinstance(text, (str, bytes)):
         readingText = text
     else:
         # assumed to be a sequence of (name, sortas)
@@ -148,7 +148,7 @@ class Delegator(object):
 
             """
             for setting in d.getSettings():
-                if isinstance(setting, string_or_bytes):
+                if isinstance(setting, (str, bytes)):
                     setting = (d, setting)
                 delegates = \
                         self.delegatedSettingsDict.setdefault(setting[1], [])
@@ -286,7 +286,7 @@ class LrsContainer(object):
                     (content.__class__.__name__,
                     self.__class__.__name__))
 
-        if convertText and isinstance(content, string_or_bytes):
+        if convertText and isinstance(content, (str, bytes)):
             content = Text(content)
 
         content.setParent(self)
@@ -580,14 +580,14 @@ class Book(Delegator):
             ts.attrs['baselineskip'] = rescale(ts.attrs['baselineskip'])
 
     def renderLrs(self, lrsFile, encoding="UTF-8"):
-        if isinstance(lrsFile, string_or_bytes):
+        if isinstance(lrsFile, (str, bytes)):
             lrsFile = codecs.open(lrsFile, "wb", encoding=encoding)
         self.render(lrsFile, outputEncodingName=encoding)
         lrsFile.close()
 
     def renderLrf(self, lrfFile):
         self.appendReferencedObjects(self)
-        if isinstance(lrfFile, string_or_bytes):
+        if isinstance(lrfFile, (str, bytes)):
             lrfFile = open(lrfFile, "wb")
         lrfWriter = LrfWriter(self.sourceencoding)
 
@@ -1488,7 +1488,7 @@ class Paragraph(LrsContainer):
         LrsContainer.__init__(self, [Text, CR, DropCaps, CharButton,
                                      LrsSimpleChar1, bytes, str])
         if text is not None:
-            if isinstance(text, string_or_bytes):
+            if isinstance(text, (str, bytes)):
                 text = Text(text)
             self.append(text)
 
@@ -1807,7 +1807,7 @@ class Span(LrsSimpleChar1, LrsContainer):
     def __init__(self, text=None, **attrs):
         LrsContainer.__init__(self, [LrsSimpleChar1, Text, bytes, str])
         if text is not None:
-            if isinstance(text, string_or_bytes):
+            if isinstance(text, (str, bytes)):
                 text = Text(text)
             self.append(text)
 
diff --git a/ebook_converter/ebooks/metadata/rtf.py b/ebook_converter/ebooks/metadata/rtf.py
index d2049b2..d09277a 100644
--- a/ebook_converter/ebooks/metadata/rtf.py
+++ b/ebook_converter/ebooks/metadata/rtf.py
@@ -6,7 +6,7 @@ import re
 
 from ebook_converter import force_unicode
 from ebook_converter.ebooks.metadata import MetaInformation
-from ebook_converter.polyglot.builtins import string_or_bytes, int_to_byte
+from ebook_converter.polyglot.builtins import int_to_byte
 
 title_pat    = re.compile(br'\{\\info.*?\{\\title(.*?)(?<!\\)\}', re.DOTALL)
 author_pat   = re.compile(br'\{\\info.*?\{\\author(.*?)(?<!\\)\}', re.DOTALL)
@@ -156,7 +156,7 @@ def create_metadata(stream, options):
         md.append(r'{\title %s}'%(title,))
     if options.authors:
         au = options.authors
-        if not isinstance(au, string_or_bytes):
+        if not isinstance(au, (str, bytes)):
             au = ', '.join(au)
         author = encode(au)
         md.append(r'{\author %s}'%(author,))
diff --git a/ebook_converter/ebooks/metadata/xmp.py b/ebook_converter/ebooks/metadata/xmp.py
index d1a04eb..62226be 100644
--- a/ebook_converter/ebooks/metadata/xmp.py
+++ b/ebook_converter/ebooks/metadata/xmp.py
@@ -12,7 +12,7 @@ from ebook_converter.ebooks.metadata.book.base import Metadata
 from ebook_converter.ebooks.metadata.opf2 import dump_dict
 from ebook_converter.utils.date import parse_date, isoformat, now
 from ebook_converter.utils.localization import canonicalize_lang, lang_as_iso639_1
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems
 
 
 __license__ = 'GPL v3'
@@ -477,7 +477,7 @@ def metadata_to_xmp_packet(mi):
         'authors':('dc:creator', True), 'tags':('dc:subject', False), 'publisher':('dc:publisher', False),
     }):
         val = mi.get(prop) or ()
-        if isinstance(val, string_or_bytes):
+        if isinstance(val, (str, bytes)):
             val = [val]
         create_sequence_property(dc, tag, val, ordered)
     if not mi.is_null('pubdate'):
diff --git a/ebook_converter/ebooks/mobi/mobiml.py b/ebook_converter/ebooks/mobi/mobiml.py
index bf89f19..07cea1c 100644
--- a/ebook_converter/ebooks/mobi/mobiml.py
+++ b/ebook_converter/ebooks/mobi/mobiml.py
@@ -11,7 +11,6 @@ from ebook_converter.ebooks.oeb.stylizer import Stylizer
 from ebook_converter.ebooks.oeb.transforms.flatcss import KeyMapper
 from ebook_converter.ebooks.mobi.utils import convert_color_for_font_tag
 from ebook_converter.utils.imghdr import identify
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL v3'
@@ -143,7 +142,7 @@ class MobiMLizer(object):
         return self.fnums[self.fmap[ptsize]]
 
     def mobimlize_measure(self, ptsize):
-        if isinstance(ptsize, string_or_bytes):
+        if isinstance(ptsize, (str, bytes)):
             return ptsize
         embase = self.profile.fbase
         if round(ptsize) < embase:
@@ -186,7 +185,7 @@ class MobiMLizer(object):
             parent = bstate.nested[-1] if bstate.nested else bstate.body
             indent = istate.indent
             left = istate.left
-            if isinstance(indent, string_or_bytes):
+            if isinstance(indent, (str, bytes)):
                 indent = 0
             if indent < 0 and abs(indent) < left:
                 left += indent
@@ -307,7 +306,7 @@ class MobiMLizer(object):
         inline = bstate.inline
         content = self.preize_text(text, pre_wrap=istate.pre_wrap) if istate.preserve or istate.pre_wrap else [text]
         for item in content:
-            if isinstance(item, string_or_bytes):
+            if isinstance(item, (str, bytes)):
                 if len(inline) == 0:
                     inline.text = (inline.text or '') + item
                 else:
@@ -318,7 +317,7 @@ class MobiMLizer(object):
 
     def mobimlize_elem(self, elem, stylizer, bstate, istates,
             ignore_valign=False):
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) != XHTML_NS:
             return
         style = stylizer.style(elem)
diff --git a/ebook_converter/ebooks/mobi/writer2/serializer.py b/ebook_converter/ebooks/mobi/writer2/serializer.py
index 61dac45..c1f2587 100644
--- a/ebook_converter/ebooks/mobi/writer2/serializer.py
+++ b/ebook_converter/ebooks/mobi/writer2/serializer.py
@@ -9,7 +9,6 @@ from ebook_converter.ebooks.mobi.utils import is_guide_ref_start
 from ebook_converter.ebooks.oeb.base import (
     OEB_DOCS, XHTML, XHTML_NS, XML_NS, namespace, prefixname, urlnormalize
 )
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL v3'
@@ -306,7 +305,7 @@ class Serializer(object):
 
     def serialize_elem(self, elem, item, nsrmap=NSRMAP):
         buf = self.buf
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
             or namespace(elem.tag) not in nsrmap:
             return
         tag = prefixname(elem.tag, nsrmap)
diff --git a/ebook_converter/ebooks/odt/input.py b/ebook_converter/ebooks/odt/input.py
index 3b1baff..ef44622 100644
--- a/ebook_converter/ebooks/odt/input.py
+++ b/ebook_converter/ebooks/odt/input.py
@@ -15,7 +15,7 @@ from odf.namespaces import TEXTNS as odTEXTNS
 from ebook_converter import CurrentDir, walk
 from ebook_converter.ebooks.oeb.base import _css_logger
 from ebook_converter.utils.xml_parse import safe_xml_fromstring
-from ebook_converter.polyglot.builtins import string_or_bytes, getcwd, as_bytes
+from ebook_converter.polyglot.builtins import getcwd, as_bytes
 
 
 __license__ = 'GPL v3'
@@ -250,7 +250,7 @@ class Extract(ODF2XHTML):
         # first load the odf structure
         self.lines = []
         self._wfunc = self._wlines
-        if isinstance(odffile, string_or_bytes) \
+        if isinstance(odffile, (str, bytes)) \
                 or hasattr(odffile, 'read'):  # Added by Kovid
             self.document = odLoad(odffile)
         else:
diff --git a/ebook_converter/ebooks/oeb/base.py b/ebook_converter/ebooks/oeb/base.py
index 2aff3eb..5cf9dab 100644
--- a/ebook_converter/ebooks/oeb/base.py
+++ b/ebook_converter/ebooks/oeb/base.py
@@ -17,7 +17,7 @@ from ebook_converter import (isbytestring, as_unicode, get_types_map)
 from ebook_converter.ebooks.oeb.parse_utils import barename, XHTML_NS, namespace, XHTML, parse_html, NotHTML
 from ebook_converter.utils.cleantext import clean_xml_chars
 from ebook_converter.utils.short_uuid import uuid4
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes, itervalues
+from ebook_converter.polyglot.builtins import iteritems, itervalues
 from ebook_converter.polyglot.urllib import unquote as urlunquote
 
 
@@ -1035,7 +1035,7 @@ class Manifest(object):
                 mt = self.media_type.lower()
             except Exception:
                 mt = 'application/octet-stream'
-            if not isinstance(data, string_or_bytes):
+            if not isinstance(data, (str, bytes)):
                 pass  # already parsed
             elif mt in OEB_DOCS:
                 data = self._parse_xhtml(data)
@@ -1296,7 +1296,7 @@ class Spine(object):
         self.page_progression_direction = None
 
     def _linear(self, linear):
-        if isinstance(linear, string_or_bytes):
+        if isinstance(linear, (str, bytes)):
             linear = linear.lower()
         if linear is None or linear in ('yes', 'true'):
             linear = True
diff --git a/ebook_converter/ebooks/oeb/normalize_css.py b/ebook_converter/ebooks/oeb/normalize_css.py
index 15f8d46..2400166 100644
--- a/ebook_converter/ebooks/oeb/normalize_css.py
+++ b/ebook_converter/ebooks/oeb/normalize_css.py
@@ -5,7 +5,7 @@ from css_parser.css import PropertyValue
 from css_parser import profile as cssprofiles, CSSParser
 from ebook_converter.tinycss.fonts3 import parse_font, serialize_font_family
 from ebook_converter.ebooks.oeb.base import css_text
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems
 
 
 __license__ = 'GPL v3'
@@ -125,10 +125,10 @@ def normalize_font(cssvalue, font_family_as_list=False):
         ans = {k:DEFAULTS[k] for k in composition}
         ans.update(parse_font(val))
     if font_family_as_list:
-        if isinstance(ans['font-family'], string_or_bytes):
+        if isinstance(ans['font-family'], (str, bytes)):
             ans['font-family'] = [x.strip() for x in ans['font-family'].split(',')]
     else:
-        if not isinstance(ans['font-family'], string_or_bytes):
+        if not isinstance(ans['font-family'], (str, bytes)):
             ans['font-family'] = serialize_font_family(ans['font-family'])
     return ans
 
diff --git a/ebook_converter/ebooks/oeb/parse_utils.py b/ebook_converter/ebooks/oeb/parse_utils.py
index 2f93e66..b40227c 100644
--- a/ebook_converter/ebooks/oeb/parse_utils.py
+++ b/ebook_converter/ebooks/oeb/parse_utils.py
@@ -6,7 +6,7 @@ from ebook_converter import xml_replace_entities, force_unicode
 from ebook_converter.utils.xml_parse import safe_xml_fromstring
 from ebook_converter.constants import filesystem_encoding
 from ebook_converter.ebooks.chardet import xml_to_unicode, strip_encoding_declarations
-from ebook_converter.polyglot.builtins import iteritems, itervalues, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems, itervalues
 
 
 __license__ = 'GPL v3'
@@ -96,7 +96,7 @@ def html5_parse(data, max_nesting_depth=100):
     # Check that the asinine HTML 5 algorithm did not result in a tree with
     # insane nesting depths
     for x in data.iterdescendants():
-        if isinstance(x.tag, string_or_bytes) and not len(x):  # Leaf node
+        if isinstance(x.tag, (str, bytes)) and not len(x):  # Leaf node
             depth = node_depth(x)
             if depth > max_nesting_depth:
                 raise ValueError('HTML 5 parsing resulted in a tree with nesting'
@@ -294,7 +294,7 @@ def parse_html(data, log=None, decoder=None, preprocessor=None,
         nroot = etree.Element(XHTML('html'),
             nsmap={None: XHTML_NS}, attrib=attrib)
         for elem in data.iterdescendants():
-            if isinstance(elem.tag, string_or_bytes) and \
+            if isinstance(elem.tag, (str, bytes)) and \
                 namespace(elem.tag) == ns:
                 elem.tag = XHTML(barename(elem.tag))
         for elem in data:
diff --git a/ebook_converter/ebooks/oeb/polish/split.py b/ebook_converter/ebooks/oeb/polish/split.py
index 6fd8d46..814525d 100644
--- a/ebook_converter/ebooks/oeb/polish/split.py
+++ b/ebook_converter/ebooks/oeb/polish/split.py
@@ -1,5 +1,4 @@
 import copy, os, re
-from ebook_converter.polyglot.builtins import string_or_bytes
 import urllib.parse
 
 from ebook_converter.ebooks.oeb.base import barename, XPNSMAP, XPath, OPF, XHTML, OEB_DOCS
@@ -393,9 +392,9 @@ def merge_html(container, names, master, insert_page_breaks=False):
 
         first_child = ''
         for first_child in children:
-            if not isinstance(first_child, string_or_bytes):
+            if not isinstance(first_child, (str, bytes)):
                 break
-        if isinstance(first_child, string_or_bytes):
+        if isinstance(first_child, (str, bytes)):
             # body contained only text, no tags
             first_child = body.makeelement(XHTML('p'))
             first_child.text, children[0] = children[0], first_child
@@ -431,7 +430,7 @@ def merge_html(container, names, master, insert_page_breaks=False):
                 a.set('href', '#' + amap[q])
 
         for child in children:
-            if isinstance(child, string_or_bytes):
+            if isinstance(child, (str, bytes)):
                 add_text(master_body, child)
             else:
                 master_body.append(copy.deepcopy(child))
diff --git a/ebook_converter/ebooks/oeb/transforms/flatcss.py b/ebook_converter/ebooks/oeb/transforms/flatcss.py
index dfa5379..1110aef 100644
--- a/ebook_converter/ebooks/oeb/transforms/flatcss.py
+++ b/ebook_converter/ebooks/oeb/transforms/flatcss.py
@@ -16,7 +16,7 @@ from ebook_converter.ebooks.oeb.base import (XHTML, XHTML_NS, CSS_MIME, OEB_STYL
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
 from ebook_converter.utils.filenames import ascii_filename, ascii_text
 from ebook_converter.utils.icu import numeric_sort_key
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes
+from ebook_converter.polyglot.builtins import iteritems
 
 
 __license__ = 'GPL v3'
@@ -351,7 +351,7 @@ class CSSFlattener(object):
                     cssdict[property] = "%0.5fem" % (value / fsize)
 
     def flatten_node(self, node, stylizer, names, styles, pseudo_styles, psize, item_id, recurse=True):
-        if not isinstance(node.tag, string_or_bytes) \
+        if not isinstance(node.tag, (str, bytes)) \
            or namespace(node.tag) != XHTML_NS:
             return
         tag = barename(node.tag)
diff --git a/ebook_converter/ebooks/oeb/transforms/manglecase.py b/ebook_converter/ebooks/oeb/transforms/manglecase.py
index dcadbb9..4e55696 100644
--- a/ebook_converter/ebooks/oeb/transforms/manglecase.py
+++ b/ebook_converter/ebooks/oeb/transforms/manglecase.py
@@ -6,7 +6,6 @@ from ebook_converter.ebooks.oeb.base import XHTML, XHTML_NS
 from ebook_converter.ebooks.oeb.base import CSS_MIME
 from ebook_converter.ebooks.oeb.base import namespace
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL v3'
@@ -95,7 +94,7 @@ class CaseMangler(object):
                 last = child
 
     def mangle_elem(self, elem, stylizer):
-        if not isinstance(elem.tag, string_or_bytes) or \
+        if not isinstance(elem.tag, (str, bytes)) or \
            namespace(elem.tag) != XHTML_NS:
             return
         children = list(elem)
diff --git a/ebook_converter/ebooks/pdb/header.py b/ebook_converter/ebooks/pdb/header.py
index fbcee72..0f176d7 100644
--- a/ebook_converter/ebooks/pdb/header.py
+++ b/ebook_converter/ebooks/pdb/header.py
@@ -5,7 +5,6 @@ Read the header data from a pdb file.
 import re
 import struct
 import time
-from ebook_converter.polyglot.builtins import long_type
 
 
 __license__ = 'GPL v3'
@@ -83,6 +82,6 @@ class PdbHeaderBuilder(object):
 
         offset = 78 + (8 * nrecords) + 2
         for id, record in enumerate(section_lengths):
-            out_stream.write(struct.pack('>LBBBB', long_type(offset), 0, 0, 0, 0))
+            out_stream.write(struct.pack('>LBBBB', int(offset), 0, 0, 0, 0))
             offset += record
         out_stream.write(b'\x00\x00')
diff --git a/ebook_converter/ebooks/txt/markdownml.py b/ebook_converter/ebooks/txt/markdownml.py
index 192be2d..1954179 100644
--- a/ebook_converter/ebooks/txt/markdownml.py
+++ b/ebook_converter/ebooks/txt/markdownml.py
@@ -8,7 +8,6 @@ from functools import partial
 from ebook_converter.ebooks.htmlz.oeb2html import OEB2HTML
 from ebook_converter.ebooks.oeb.base import XHTML, XHTML_NS, barename, namespace, rewrite_links
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL 3'
@@ -110,10 +109,10 @@ class MarkdownMLizer(OEB2HTML):
         '''
 
         # We can only processes tags. If there isn't a tag return any text.
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) != XHTML_NS:
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) == XHTML_NS \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) == XHTML_NS \
                     and elem.tail:
                 return [elem.tail]
             return ['']
diff --git a/ebook_converter/ebooks/txt/processor.py b/ebook_converter/ebooks/txt/processor.py
index 7fbe45f..9a733ee 100644
--- a/ebook_converter/ebooks/txt/processor.py
+++ b/ebook_converter/ebooks/txt/processor.py
@@ -8,7 +8,7 @@ from ebook_converter.ebooks.metadata.opf2 import OPFCreator
 
 from ebook_converter.ebooks.conversion.preprocess import DocAnalysis
 from ebook_converter.utils.cleantext import clean_ascii_chars
-from ebook_converter.polyglot.builtins import iteritems, long_type
+from ebook_converter.polyglot.builtins import iteritems
 
 
 __license__ = 'GPL v3'
@@ -62,7 +62,7 @@ def split_txt(txt, epub_split_size_kb=0):
             txt = txt.encode('utf-8')
         length_byte = len(txt)
         # Calculating the average chunk value for easy splitting as EPUB (+2 as a safe margin)
-        chunk_size = long_type(length_byte / (int(length_byte / (epub_split_size_kb * 1024)) + 2))
+        chunk_size = int(length_byte / (int(length_byte / (epub_split_size_kb * 1024)) + 2))
         # if there are chunks with a superior size then go and break
         parts = txt.split(b'\n\n')
         lengths = tuple(map(len, parts))
diff --git a/ebook_converter/ebooks/txt/textileml.py b/ebook_converter/ebooks/txt/textileml.py
index 4192416..54e90d3 100644
--- a/ebook_converter/ebooks/txt/textileml.py
+++ b/ebook_converter/ebooks/txt/textileml.py
@@ -10,7 +10,6 @@ from ebook_converter.ebooks.oeb.base import XHTML, XHTML_NS, barename, namespace
 from ebook_converter.ebooks.oeb.stylizer import Stylizer
 from ebook_converter.ebooks import unit_convert
 from ebook_converter.ebooks.textile.unsmarten import unsmarten
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL 3'
@@ -225,10 +224,10 @@ class TextileMLizer(OEB2HTML):
         '''
 
         # We can only processes tags. If there isn't a tag return any text.
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) != XHTML_NS:
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) == XHTML_NS \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) == XHTML_NS \
                     and elem.tail:
                 return [elem.tail]
             return ['']
diff --git a/ebook_converter/ebooks/txt/txtml.py b/ebook_converter/ebooks/txt/txtml.py
index 78e1f65..ae16e9b 100644
--- a/ebook_converter/ebooks/txt/txtml.py
+++ b/ebook_converter/ebooks/txt/txtml.py
@@ -4,7 +4,6 @@ Transform OEB content into plain text
 import re
 
 from lxml import etree
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL 3'
@@ -189,10 +188,10 @@ class TXTMLizer(object):
         '''
         from ebook_converter.ebooks.oeb.base import XHTML_NS, barename, namespace
 
-        if not isinstance(elem.tag, string_or_bytes) \
+        if not isinstance(elem.tag, (str, bytes)) \
            or namespace(elem.tag) != XHTML_NS:
             p = elem.getparent()
-            if p is not None and isinstance(p.tag, string_or_bytes) and namespace(p.tag) == XHTML_NS \
+            if p is not None and isinstance(p.tag, (str, bytes)) and namespace(p.tag) == XHTML_NS \
                     and elem.tail:
                 return [elem.tail]
             return ['']
diff --git a/ebook_converter/library/catalogs/bibtex.py b/ebook_converter/library/catalogs/bibtex.py
index aed98e9..d96a6cf 100644
--- a/ebook_converter/library/catalogs/bibtex.py
+++ b/ebook_converter/library/catalogs/bibtex.py
@@ -6,7 +6,6 @@ from ebook_converter.customize import CatalogPlugin
 from ebook_converter.library.catalogs import FIELDS, TEMPLATE_ALLOWED_FIELDS
 from ebook_converter.customize.conversion import DummyReporter
 from ebook_converter.ebooks.metadata import format_isbn
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 __license__ = 'GPL v3'
@@ -208,11 +207,11 @@ class BIBTEX(CatalogPlugin):
                     bibtex_entry.append('year = "%s"' % item.year)
                     bibtex_entry.append('month = "%s"' % bibtexdict.utf8ToBibtex(strftime("%b", item)))
 
-                elif field.startswith('#') and isinstance(item, string_or_bytes):
+                elif field.startswith('#') and isinstance(item, (str, bytes)):
                     bibtex_entry.append('custom_%s = "%s"' % (field[1:],
                         bibtexdict.utf8ToBibtex(item)))
 
-                elif isinstance(item, string_or_bytes):
+                elif isinstance(item, (str, bytes)):
                     # elif field in ['title', 'publisher', 'cover', 'uuid', 'ondevice',
                     # 'author_sort', 'series', 'title_sort'] :
                     bibtex_entry.append('%s = "%s"' % (field, bibtexdict.utf8ToBibtex(item)))
@@ -346,7 +345,7 @@ class BIBTEX(CatalogPlugin):
             bibtexc.ascii_bibtex = True
 
         # Check citation choice and go to default in case of bad CLI
-        if isinstance(opts.impcit, string_or_bytes) :
+        if isinstance(opts.impcit, (str, bytes)) :
             if opts.impcit == 'False' :
                 citation_bibtex= False
             elif opts.impcit == 'True' :
@@ -358,7 +357,7 @@ class BIBTEX(CatalogPlugin):
             citation_bibtex= opts.impcit
 
         # Check add file entry and go to default in case of bad CLI
-        if isinstance(opts.addfiles, string_or_bytes) :
+        if isinstance(opts.addfiles, (str, bytes)) :
             if opts.addfiles == 'False' :
                 addfiles_bibtex = False
             elif opts.addfiles == 'True' :
diff --git a/ebook_converter/polyglot/builtins.py b/ebook_converter/polyglot/builtins.py
index d01e1ad..6c40590 100644
--- a/ebook_converter/polyglot/builtins.py
+++ b/ebook_converter/polyglot/builtins.py
@@ -21,10 +21,7 @@ def as_bytes(x, encoding='utf-8'):
         return bytes(x)
     if isinstance(x, memoryview):
         return x.tobytes()
-    ans = str(x)
-    if isinstance(ans, str):
-        ans = ans.encode(encoding)
-    return ans
+    return str(x).encode(encoding)
 
 
 def as_unicode(x, encoding='utf-8', errors='strict'):
@@ -45,9 +42,6 @@ def reraise(tp, value, tb=None):
         tb = None
 
 
-string_or_bytes = str, bytes
-string_or_unicode = str
-long_type = int
 raw_input = input
 getcwd = os.getcwd
 getenv = os.getenv
diff --git a/ebook_converter/utils/config.py b/ebook_converter/utils/config.py
index 3c773fb..6d48a86 100644
--- a/ebook_converter/utils/config.py
+++ b/ebook_converter/utils/config.py
@@ -14,7 +14,7 @@ from ebook_converter.utils.config_base import (
     tweaks, from_json, to_json
 )
 from ebook_converter.utils.lock import ExclusiveFile
-from ebook_converter.polyglot.builtins import string_or_bytes, native_string_type
+from ebook_converter.polyglot.builtins import native_string_type
 
 
 __license__ = 'GPL v3'
@@ -191,7 +191,7 @@ class OptionParser(optparse.OptionParser):
                 upper.__dict__[dest] = lower.__dict__[dest]
 
     def add_option_group(self, *args, **kwargs):
-        if isinstance(args[0], string_or_bytes):
+        if isinstance(args[0], (str, bytes)):
             args = list(args)
             args[0] = native_string_type(args[0])
         return optparse.OptionParser.add_option_group(self, *args, **kwargs)
diff --git a/ebook_converter/utils/img.py b/ebook_converter/utils/img.py
index 8cedc5c..c2aa997 100644
--- a/ebook_converter/utils/img.py
+++ b/ebook_converter/utils/img.py
@@ -17,7 +17,6 @@ from ebook_converter.ptempfile import TemporaryDirectory
 from ebook_converter.utils.config_base import tweaks
 from ebook_converter.utils.filenames import atomic_rename
 from ebook_converter.utils.imghdr import what
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 # Utilities {{{
 # imageops, imageops_err = plugins['imageops']
@@ -505,7 +504,7 @@ def quantize_image(img, max_colors=256, dither=True, palette=''):
     img = image_from_data(img)
     if img.hasAlphaChannel():
         img = blend_image(img)
-    if palette and isinstance(palette, string_or_bytes):
+    if palette and isinstance(palette, (str, bytes)):
         palette = palette.split()
     return imageops.quantize(img, max_colors, dither, [QColor(x).rgb() for x in palette])
 
diff --git a/ebook_converter/utils/imghdr.py b/ebook_converter/utils/imghdr.py
index c987e2a..886013b 100644
--- a/ebook_converter/utils/imghdr.py
+++ b/ebook_converter/utils/imghdr.py
@@ -6,7 +6,6 @@ import os
 
 from ebook_converter.utils.speedups import ReadOnlyFileBuffer
 from ebook_converter.constants import ispy3
-from ebook_converter.polyglot.builtins import string_or_bytes
 
 
 HSIZE = 120
@@ -15,7 +14,7 @@ HSIZE = 120
 def what(file, h=None):
     ' Recognize image headers '
     if h is None:
-        if isinstance(file, string_or_bytes):
+        if isinstance(file, (str, bytes)):
             with lopen(file, 'rb') as f:
                 h = f.read(HSIZE)
         else:
diff --git a/ebook_converter/utils/ipc/launch.py b/ebook_converter/utils/ipc/launch.py
index 7c05124..b0bc41b 100644
--- a/ebook_converter/utils/ipc/launch.py
+++ b/ebook_converter/utils/ipc/launch.py
@@ -5,7 +5,7 @@ from ebook_converter.constants import isosx, isfrozen, filesystem_encoding, ispy
 from ebook_converter.utils.config import prefs
 from ebook_converter.ptempfile import PersistentTemporaryFile, base_dir
 from ebook_converter.utils.serialize import msgpack_dumps
-from ebook_converter.polyglot.builtins import iteritems, string_or_bytes, environ_item, native_string_type, getcwd
+from ebook_converter.polyglot.builtins import iteritems, environ_item, native_string_type, getcwd
 from ebook_converter.polyglot.binary import as_hex_unicode
 try:
     import win32process
@@ -191,7 +191,7 @@ class Worker(object):
         _cwd = cwd
         if priority is None:
             priority = prefs['worker_process_priority']
-        cmd = [exe] if isinstance(exe, string_or_bytes) else exe
+        cmd = [exe] if isinstance(exe, (str, bytes)) else exe
         args = {
                 'env' : env,
                 'cwd' : _cwd,
diff --git a/ebook_converter/utils/ipc/simple_worker.py b/ebook_converter/utils/ipc/simple_worker.py
index c1cb18a..744055a 100644
--- a/ebook_converter/utils/ipc/simple_worker.py
+++ b/ebook_converter/utils/ipc/simple_worker.py
@@ -8,7 +8,7 @@ from ebook_converter.utils.ipc import eintr_retry_call
 from ebook_converter.utils.ipc.launch import Worker
 from ebook_converter.utils.serialize import msgpack_loads, msgpack_dumps
 from ebook_converter.utils.monotonic import monotonic
-from ebook_converter.polyglot.builtins import string_or_bytes, environ_item
+from ebook_converter.polyglot.builtins import environ_item
 from ebook_converter.polyglot.binary import as_hex_unicode, from_hex_bytes
 
 
@@ -162,7 +162,7 @@ def start_pipe_worker(command, env=None, priority='normal', **process_args):
         args['close_fds'] = True
 
     exe = w.executable
-    cmd = [exe] if isinstance(exe, string_or_bytes) else exe
+    cmd = [exe] if isinstance(exe, (str, bytes)) else exe
     p = subprocess.Popen(cmd + ['--pipe-worker', command], **args)
     return p
 
diff --git a/ebook_converter/utils/zipfile.py b/ebook_converter/utils/zipfile.py
index 27a83fb..56b09ec 100644
--- a/ebook_converter/utils/zipfile.py
+++ b/ebook_converter/utils/zipfile.py
@@ -10,7 +10,7 @@ from tempfile import SpooledTemporaryFile
 from ebook_converter import sanitize_file_name
 from ebook_converter.constants import filesystem_encoding
 from ebook_converter.ebooks.chardet import detect
-from ebook_converter.polyglot.builtins import string_or_bytes, getcwd, as_bytes
+from ebook_converter.polyglot.builtins import getcwd, as_bytes
 
 try:
     import zlib  # We may need its compression method
@@ -749,7 +749,7 @@ class ZipFile:
         self.comment = b''
 
         # Check if we were passed a file-like object
-        if isinstance(file, string_or_bytes):
+        if isinstance(file, (str, bytes)):
             self._filePassed = 0
             self.filename = file
             modeDict = {'r' : 'rb', 'w': 'wb', 'a' : 'r+b'}