svoid test_StringTrie() {
  Map<S, Int> map = littreemap("hello" := 1, "hella" := 2);
  StringTrie<Int> trie = asStringTrie(map); 
  assertEquals(map, trie.asMap());
  print(trie);
  assertEquals(littreeset("hell"), trie.childStrings());
  
  // add in different order, check again
  trie = new StringTrie; 
  trie.add("hello" := 1);
  trie.add("hella" := 2);
  assertEquals(map, trie.asMap());
  print(trie);
  assertEquals(littreeset("hell"), trie.childStrings());
  
  map.put("hell" := 3);
  assertEquals(map, asStringTrie(map).asMap());
  
  map = litcimap("HE" := 1, "hello" := 2);
  assertEquals(map, assertCIMap(asStringTrie(map).asMap()));
  print(asStringTrie(map));
  
  map = litmap("" := 5, "bla" := 6);
  assertEquals(map, asStringTrie(map).asMap());
  print(asStringTrie(map));
}