def __contains__(self, item):
if isinstance(item, Revision):<EOL><INDENT>return item.key in self._revisions<EOL><DEDENT>elif isinstance(item, str):<EOL><INDENT>return item in self._revisions<EOL><DEDENT>else:<EOL><INDENT>raise TypeError("<STR_LIT>")<EOL><DEDENT>
Check if index contains `item`.

:param item: The item to search for
:type  item: ``str``, :class:`Revision` or :class:`LazyRevision`

:return: ``True`` for contains, ``False`` for not.