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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_last_version(self, filename=None, session=None, **kwargs):
 """Get the most recent version of a file in GridFS by ``"filename"`` or metadata fields. Equivalent to calling :meth:`get_version` with the default `version` (``-1``). :Parameters: - `filename`: ``"filename"`` of the file to get, or `None` - `session` (optional):
 a :class:`~pymongo.client_session.ClientSession` - `**kwargs` (optional):
 find files by custom metadata. .. versionchanged:: 3.6 Added ``session`` parameter. """

        return self.get_version(filename=filename, session=session, **kwargs)