code: func Formatter(id Implementation, form Format) string {
  	checkFormat(form)
  	return formatUuid(id.Bytes(), form)
  }
docs: // Formatter will return a string representation of the given UUID.
  //
  // Use this for one time formatting when setting the Format using
  // uuid.SwitchFormat would be overkill.
  //
  // A valid format will have 5 groups of [%x|%X] or follow the pattern,
  // *%[xX]*%[xX]*%[xX]*%[xX]*%[xX]*. If the supplied format does not meet this
  // standard the function will panic. Note any extra uses of [%] outside of the
  // [%x|%X] will also cause a panic.