validateNames function
Implementation
bool validateNames(String firstName, String lastName, Iterable<String> lines) {
List<String> words = [];
for (var l in lines) {
words.addAll(extractWords(l).map((a) => a.toLowerCase()));
}
final isFirstNameValid = firstName.toLowerCase().split(" ").every((a) => words.contains(a.toLowerCase()));
final isLastNameValid = lastName.toLowerCase().split(" ").every((a) => words.contains(a.toLowerCase()));
final res = isLastNameValid && isFirstNameValid;
return res;
}