code: func (f SelectFlag) String() string {
  	var flags [2]string
  	var n int
  	if f&SelectCopy != 0 {
  		flags[n] = "copy"
  		n++
  	}
  	if f&SelectUnique != 0 {
  		flags[n] = "unique"
  		n++
  	}
  	return "[" + strings.Join(flags[:n], "|") + "]"
  }
docs: // String represetns flag as string.