mask method
Masks part of the string for privacy.
Example:
"1234567890".mask(start: 3, end: 7); // "123****890"
Implementation
String mask({int? start, int? end, String maskChar = '*'}) {
if (this == null || this!.isEmpty) return '';
final s = this!;
if (start == null && end == null) return s;
start ??= 0;
end ??= this!.length;
if (start >= s.length || end <= start) return s;
final masked = s.replaceRange(
start,
end > s.length ? s.length : end,
maskChar * (end - start),
);
return masked;
}