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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 get_subject(self, data):
 """ Try to get a unique ID from the object. By default, this will be the 'id' field of any given object, or a field specified by the 'rdfSubject' property. If no other option is available, a UUID will be generated. """

        if not isinstance(data, Mapping):
            return None
        if data.get(self.subject):
            return data.get(self.subject)
        return uuid.uuid4().urn