code: func (f *Formatter) WriteWrapped(str string, a ...interface{}) error {
  	if f.Wrap == 0 {
  		return f.Write(str, a...)
  	}
  	text := fmt.Sprintf(str, a...)
  	strs := wrapString(text, f.Wrap-f.IndentLevel)
  	for _, substr := range strs {
  		if err := f.Write(substr); err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // WriteWrapped writes a string with the indentation set for the
  // Formatter, and wraps as needed.