[Question] How can I customize the name of the field id is retrieve by?

Im trying to have relay node compose the global id in a custom way for a specific type. Instead of using the id attribute of my object I want it to use the uuid attribute. I know that i can create a custom node class to customize how the id is encoded and decoded: http://docs.graphene-python.org/en/latest/relay/nodes/
but what i want to do Is also customize the name of the field the id is gotten from ... this code suggest that it can be done by passing id_fetcher but i Dont know where or how this function is called https://github.com/graphql-python/graphql-relay-py/blob/master/graphql_relay/node/node.py#L70