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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 modify_signature(self, signature):
 """ Modify an existing signature Can modify the content, contenttype and name. An unset attribute will not delete the attribute but leave it untouched. :param: signature a zobject.Signature object, with modified content/contentype/name, the id should be present and valid, the name does not allows to identify the signature for that operation. """

        # if no content is specified, just use a selector (id/name)
        dic = signature.to_creator(for_modify=True)

        self.request('ModifySignature', {'signature': dic})