# Source code for rl_coach.memories.non_episodic.transition_collection

    from rl_coach.core_types import Transition

    class TransitionCollection(object):
        """
        Simple python implementation of transitions collection non-episodic memories
        are constructed on top of.
        """
        def __init__(self):
            super(TransitionCollection, self).__init__()

        def append(self, transition):
            pass

        def extend(self, transitions):
            for transition in transitions:
                self.append(transition)

        def __len__(self):
            pass

        def __del__(self, range: slice):
            # NOTE: the only slice used is the form: slice(None, n)
            # NOTE: if it is easier, what we really want here is the ability to
            # constrain the size of the collection. as new transitions are added,
            # old transitions can be removed to maintain a maximum collection size.
            pass

        def __getitem__(self, key: int):
            # NOTE: we can switch to a method which fetches multiple items at a time
            # if that would significantly improve performance
            pass

        def __iter__(self):
            # this is not high priority
            pass