human
I wrote the below code

    d = control_service.create_dataset(primary=node_uuid, maximum_size=volume_size, dataset_id=dataset_id)
    def dataset_matches(dataset, state):
        return ((state.dataset_id == dataset.dataset_id) and (state.primary == dataset.primary) and (state.path is not None))
    d.addCallback((lambda dataset: loop_until_state_found(reactor, control_service.list_datasets_state, partial(dataset_matches, dataset), timeout)))
    return d

What's a good function header?

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Here's a good function header?
assistant
#Here's a good function header.

def create_dataset(reactor, control_service, node_uuid, dataset_id, volume_size, timeout=DEFAULT_TIMEOUT):