isValid method
Implementation
@override
bool isValid(String value) {
String v = strip(value);
/// phone must have 10 or 11 chars
if (v.length < 8 || v.length > 9) {
return false;
}
/// Números de 9 dígitos sempre iniciam com 9.
return !(v.length == 9 && v[0] != '9');
}