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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):
 """Convert attribute definition into a dictionary. Returns ------- dict Json-like dictionary representation of the attribute definition """

        obj = {
            'id' : self.identifier,
            'name' : self.name,
            'description' : self.description,
            'type' : self.data_type.to_dict()
        }
        if not self.default is None:
            obj['default'] = self.default
        return obj