code: func isShorterThanPossibleNormalNumber(
  	regionMetadata *PhoneMetadata,
  	number string) bool {
  
  	pat, ok := readFromRegexCache(regionMetadata.GetGeneralDesc().GetNationalNumberPattern())
  	if !ok {
  		patP := regionMetadata.GetGeneralDesc().GetNationalNumberPattern()
  		pat = regexp.MustCompile(patP)
  		writeToRegexCache(patP, pat)
  	}
  	return testNumberLengthAgainstPattern(pat, number) == TOO_SHORT
  }
docs: // Helper method to check whether a number is too short to be a regular
  // length phone number in a region.