format static method
Implementation
static String format(String cnpj) {
RegExp regExp = RegExp(r'^(\d{2})(\d{3})(\d{3})(\d{4})(\d{2})$');
return strip(cnpj).replaceAllMapped(
regExp, (Match m) => "${m[1]}.${m[2]}.${m[3]}/${m[4]}-${m[5]}");
}