base64Validate function
Implementation
bool base64Validate(String? value) {
assert(value != null, 'Expected non-null, non-empty base64 input');
return RegExp(
r'^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=|[A-Za-z0-9+\/]{4})$')
.hasMatch(value!);
}