groupAnagrams function
Group Anagrams: groups words that are anagrams of each other.
Implementation
List<List<String>> groupAnagrams(List<String> words) {
final map = <String, List<String>>{};
for (final word in words) {
final key = (word.split('')..sort()).join();
map.putIfAbsent(key, () => []).add(word);
}
return map.values.toList();
}