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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 subsystem(s):
 """Validate a |Subsystem|. Checks its state and cut. """

    node_states(s.state)
    cut(s.cut, s.cut_indices)
    if config.VALIDATE_SUBSYSTEM_STATES:
        state_reachable(s)
    return True