def devaluate(actual, expected)
      same = (Set.new(expected) == Set.new(actual))
      same ? fail(expected_message.elements(expected).not_to_match(actual)) : pass(new_message.has_same_elements_as(expected))
    end
(see Riot::AssertionMacro#devaluate)
@param [Object] expected the collection of elements that actual should not be equivalent to