def SHOULD!(m)
      RequirementLevel::Medium.new(m, false, subject, *challenges).result(true)
    end
def SHOULD!(m)
      RequirementLevel::Medium.new(m, false, subject, *challenges).result(true)
    end
@example _Recommended_ definition with isolation
   it { 'foo'.valid_encoding? }.SHOULD! equal true

 @see SHOULD