@classmethod
def _assign(cls, container, index, value):
    """Assign an element in the container to the specified value.

        Args:
            container (obj): Object that element will be assigned to.
            index (obj): Index in the container object where element will be
                assigned.
            value (obj): Value that will be assigned to the element in the
                container object.

        """
    raise NotImplementedError('This must be overwritten by the subclass.')
