code: func (v *VerbalExpression) Regex() *regexp.Regexp {
  
  	if !v.compiled {
  		v.regexp = regexp.MustCompile(
  			strings.Join([]string{
  				strings.Join(v.parts, ""),
  				`(?` + v.getFlags() + `)`,
  				v.prefixes,
  				v.expression,
  				v.suffixes}, ""))
  		v.compiled = true
  	}
  	return v.regexp
  }
docs: // Regex returns the regular expression to use to test on string.