isNANPACountry method
Checks if this is a region under the North American Numbering Plan Administration (NANPA).
regionCode
the CLDR two-letter region code.
isNANPACountry returns true if regionCode is one of the regions under NANPA.
Implementation
bool isNANPACountry(String? regionCode) {
List<String> regions =
_metadataMapLoader.countryCodeToRegionCodeMap['$_nanpaCountryCode'] ??
[];
return regionCode != null && (regions.contains(regionCode.toUpperCase()));
}