def devaluate(actual, expected)
      expected = %r[#{Regexp.escape(expected)}] if expected.kind_of?(String)
      if actual.to_s =~ expected
        fail(expected_message(expected).not_to_match(actual))
      else
        pass(new_message.matches(expected))
      end
    end
def devaluate(actual, expected)
      expected = %r[#{Regexp.escape(expected)}] if expected.kind_of?(String)
      if actual.to_s =~ expected
        fail(expected_message(expected).not_to_match(actual))
      else
        pass(new_message.matches(expected))
      end
    end
(see Riot::AssertionMacro#devaluate)
 @param [Regex, String] expected the string or regex to be used in comparison