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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 always(func: Callable[[], Generator]) -> AlwaysFixture: """Decorator that registers an 'always' fixture, which is always run before all provider state fixtures and faasport call. """

    global user_always

    if user_always is not None:
        raise RuntimeError('Multiple definitions of @always fixture.')

    as_context_manager = contextmanager(func)
    user_always = as_context_manager
    return as_context_manager