code: func NewRegexp(s string) (Regexp, error) {
  	regex, err := regexp.Compile("^(?:" + s + ")$")
  	return Regexp{
  		Regexp:   regex,
  		original: s,
  	}, err
  }
docs: // NewRegexp creates a new anchored Regexp and returns an error if the
  // passed-in regular expression does not compile.