Update an Amazon SageMaker ``Endpoint`` according to the endpoint configuration specified in the request

        Raise an error if endpoint with endpoint_name does not exist.

        Args:
            endpoint_name (str): Name of the Amazon SageMaker ``Endpoint`` to update.
            endpoint_config_name (str): Name of the Amazon SageMaker endpoint configuration to deploy.

        Returns:
            str: Name of the Amazon SageMaker ``Endpoint`` being updated.

def update_endpoint(self, endpoint_name, endpoint_config_name):
        """ Update an Amazon SageMaker ``Endpoint`` according to the endpoint configuration specified in the request

        Raise an error if endpoint with endpoint_name does not exist.

        Args:
            endpoint_name (str): Name of the Amazon SageMaker ``Endpoint`` to update.
            endpoint_config_name (str): Name of the Amazon SageMaker endpoint configuration to deploy.

        Returns:
            str: Name of the Amazon SageMaker ``Endpoint`` being updated.
        """
        if not _deployment_entity_exists(lambda: self.sagemaker_client.describe_endpoint(EndpointName=endpoint_name)):
            raise ValueError('Endpoint with name "{}" does not exist; please use an existing endpoint name'
                             .format(endpoint_name))

        self.sagemaker_client.update_endpoint(EndpointName=endpoint_name,
                                              EndpointConfigName=endpoint_config_name)
        return endpoint_name