code: func Not(x interface{}) Matcher {
  	if m, ok := x.(Matcher); ok {
  		return notMatcher{m}
  	}
  	return notMatcher{Eq(x)}
  }
docs: // Not reverses the results of its given child matcher.
  //
  // Example usage:
  //   Not(Eq(5)).Matches(4) // returns true
  //   Not(Eq(5)).Matches(5) // returns false