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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 to_pb(self):
 """Converts the column family to a protobuf. :rtype: :class:`.table_v2_pb2.ColumnFamily` :returns: The converted current object. """

        if self.gc_rule is None:
            return table_v2_pb2.ColumnFamily()
        else:
            return table_v2_pb2.ColumnFamily(gc_rule=self.gc_rule.to_pb())