code: func Is(s SkipT, requirements ...Test) {
  	for _, r := range requirements {
  		isValid := r()
  		if !isValid {
  			requirementFunc := runtime.FuncForPC(reflect.ValueOf(r).Pointer()).Name()
  			s.Skip(fmt.Sprintf("unmatched requirement %s", extractRequirement(requirementFunc)))
  		}
  	}
  }
docs: // Is checks if the environment satisfies the requirements
  // for the test to run or skips the tests.