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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):
 """Return a dict representation of KnwKBDDEF."""

        return {'field': self.output_tag,
                'expression': self.search_expression,
                'coll_id': self.id_collection,
                'collection': self.collection.name
                if self.collection else None}