def METHOD_NAME():
    old_commutative_index = copy(commutative.index)
    old_commutative_facts = copy(commutative.facts)
    old_associative_index = copy(associative.index)
    old_associative_facts = copy(associative.facts)
    try:
        yield
    finally:
        commutative.index = old_commutative_index
        commutative.facts = old_commutative_facts
        associative.index = old_associative_index
        associative.facts = old_associative_facts