@staticmethod
def compute(mechanism, subsystem, purviews, cause_purviews, effect_purviews):
    """Compute a |Concept| for a mechanism, in this |Subsystem| with the
        provided purviews.
        """
    concept = subsystem.concept(mechanism, purviews=purviews,
        cause_purviews=cause_purviews, effect_purviews=effect_purviews)
    concept.subsystem = None
    return concept
