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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 _fetch(self):
 """wrapped by `fetch` override that in subclasses to customize"""

        if 'uri' in self._meta_data:
            error = "There was an attempt to assign a new uri to this "\
                    "resource, the _meta_data['uri'] is %s and it should"\
                    " not be changed." % (self._meta_data['uri'])
            raise URICreationCollision(error)
        # Make convenience variable with short names for this method.
        _create_uri = self._meta_data['container']._meta_data['uri']
        session = self._meta_data['bigip']._meta_data['icr_session']
        # Invoke the REST operation on the device.
        response = session.post(_create_uri, json={})
        # Make new instance of self
        return self._produce_instance(response)