bool isValidEmail(String? inputString, {bool isRequired = false}) {
  bool isInputStringValid = false;
  if (!isRequired && (inputString == null ? true : inputString.isEmpty)) {
    isInputStringValid = true;
  }
  if (inputString != null && inputString.isNotEmpty) {
    const pattern =
        r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
    final regExp = RegExp(pattern);
    isInputStringValid = regExp.hasMatch(inputString);
  }
  return isInputStringValid;
}
