deleteKeys method
Removes the keys at indices. Sorted and walked back to front
internally, so an earlier removal never shifts a later index still
waiting to be read — the caller hands over indices into the table as
it was before this call, in whatever order it likes.
Implementation
void deleteKeys(List<int> indices) {
final sorted = List<int>.of(indices)..sort();
for (var i = sorted.length - 1; i >= 0; i--) {
final index = sorted[i];
if (index < 0 || index >= _keys.length) continue;
_keys.removeAt(index);
}
}