def MUST_NOT(m)
      RequirementLevel::High.new(m, true, subject, *challenges).result
    end
def MUST_NOT(m)
      RequirementLevel::High.new(m, true, subject, *challenges).result
    end
This phrase, or the phrase "SHALL NOT", mean that the
 definition is an absolute prohibition of the specification.

 @example _Absolute prohibition_ definition
   it { 'foo'.size }.MUST_NOT equal 42

 @param m [#matches?] The matcher.

 @return [Result::Fail, Result::Pass] Report if the spec pass or fail.