Return storage statistics about the library

        Returns
        -------
        dictionary of storage stats

def stats(self):
        """
        Return storage statistics about the library

        Returns
        -------
        dictionary of storage stats
        """

        res = {}
        db = self._collection.database
        conn = db.connection
        res['sharding'] = {}
        try:
            sharding = conn.config.databases.find_one({'_id': db.name})
            if sharding:
                res['sharding'].update(sharding)
            res['sharding']['collections'] = list(conn.config.collections.find({'_id': {'$regex': '^' + db.name + r"\..*"}}))
        except OperationFailure:
            # Access denied
            pass
        res['dbstats'] = db.command('dbstats')
        res['chunks'] = db.command('collstats', self._collection.name)
        res['versions'] = db.command('collstats', self._versions.name)
        res['snapshots'] = db.command('collstats', self._snapshots.name)
        res['totals'] = {'count': res['chunks']['count'],
                         'size': res['chunks']['size'] + res['versions']['size'] + res['snapshots']['size'],
                         }
        return res