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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 the schema as a dict ready to be serialized. """

        schema = super(Schema, self).to_dict()
        schema['$schema'] = "http://json-schema.org/draft-04/schema#"
        if self._id:
            schema['id'] = self._id
        if self._desc:
            schema['description'] = self._desc
        return schema