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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_dict(self):
 """Serialize representation of the table for local caching."""

        return {'schema': self.schema, 'name': self.name, 'columns': [col.to_dict() for col in self._columns],
                'foreign_keys': self.foreign_keys.to_dict(), 'ref_keys': self.ref_keys.to_dict()}