last method
Gets the last len grapheme clusters of this string.
Uses the characters package to correctly handle multi-codepoint sequences such as emoji with skin-tone modifiers or ZWJ sequences.
Returns the full string if len is greater than the grapheme length.
Implementation
String last(int len) {
if (isEmpty || len <= 0) return '';
final Characters chars = characters;
final int charLength = chars.length;
if (len >= charLength) return this;
// skip() avoids allocating a full List<String> for large strings
return chars.skip(charLength - len).string;
}