findForeignLetterPrevious method
Implementation
bool findForeignLetterPrevious(int index) {
if (index < 0) return false;
final foreign = ['w', 'f', 'k', 'K', 'c', 'z', 'H', 'R', 'L', 'Z', 'C'];
for (int i = index; i >= 0; i--) {
final letter = latin[i];
if (foreign.contains(letter)) return true;
}
return false;
}