code: func isNumberMatchWithOneNumber(
  	firstNumber *PhoneNumber, secondNumber string) MatchType {
  	// First see if the second number has an implicit country calling
  	// code, by attempting to parse it.
  	secondNumberAsProto, err := Parse(secondNumber, UNKNOWN_REGION)
  	if err == nil {
  		return isNumberMatchWithNumbers(firstNumber, secondNumberAsProto)
  	}
  	if err != ErrInvalidCountryCode {
  		return NOT_A_NUMBER
  	}
  	// The second number has no country calling code. EXACT_MATCH is no
  	// longer possible. We parse it as if the region was the same as that
  	// for the first number, and if EXACT_MATCH is returned, we replace
  	// this with NSN_MATCH.
  	firstNumberRegion := GetRegionCodeForCountryCode(int(firstNumber.GetCountryCode()))
  
  	if firstNumberRegion != UNKNOWN_REGION {
  		secondNumberWithFirstNumberRegion, err :=
  			Parse(secondNumber, firstNumberRegion)
  		if err != nil {
  			return NOT_A_NUMBER
  		}
  		match := isNumberMatchWithNumbers(
  			firstNumber, secondNumberWithFirstNumberRegion)
  		if match == EXACT_MATCH {
  			return NSN_MATCH
  		}
  		return match
  	} else {
  		// If the first number didn't have a valid country calling
  		// code, then we parse the second number without one as well.
  		var secondNumberProto *PhoneNumber
  		err := parseHelper(secondNumber, "", false, false, secondNumberProto)
  		if err != nil {
  			return NOT_A_NUMBER
  		}
  		return isNumberMatchWithNumbers(firstNumber, secondNumberProto)
  	}
  }
docs: // Takes two phone numbers and compares them for equality. This is a
  // convenience wrapper for IsNumberMatch(PhoneNumber, PhoneNumber). No
  // default region is known.