code: func (fs *FlagSet) String(names []string, value string, usage string) *string {
  	p := new(string)
  	fs.StringVar(p, names, value, usage)
  	return p
  }
docs: // String defines a string flag with specified name, default value, and usage string.
  // The return value is the address of a string variable that stores the value of the flag.