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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 table(self):
 """a ```pylsdj.Table``` referencing the instrument's table, or None if the instrument doesn't have a table"""

        if hasattr(self.data, 'table_on') and self.data.table_on:
            assert_index_sane(self.data.table, len(self.song.tables))
            return self.song.tables[self.data.table]