Check that the generation on the BIG-IP® matches the object

        This will do a get to the objects URI and check that the generation
        returned in the JSON matches the one the object currently has.  If it
        does not it will raise the `GenerationMismatch` exception.

def _check_generation(self):
        """Check that the generation on the BIG-IP® matches the object

        This will do a get to the objects URI and check that the generation
        returned in the JSON matches the one the object currently has.  If it
        does not it will raise the `GenerationMismatch` exception.
        """
        session = self._meta_data['bigip']._meta_data['icr_session']
        response = session.get(self._meta_data['uri'])
        current_gen = response.json().get('generation', None)
        if current_gen is not None and current_gen != self.generation:
            error_message = ("The generation of the object on the BigIP "
                             + "(" + str(current_gen) + ")"
                             + " does not match the current object"
                             + "(" + str(self.generation) + ")")
            raise GenerationMismatch(error_message)