message: add argument guide and improve collection
diff: @@ -38,7 +38,7 @@ export default class Collection<K, V> extends Map<K, V> {
  }
  filter(callback: (value: V, key: K) => boolean) {
  - const relevant = new Collection();
  + const relevant = new Collection<K, V>();
  this.forEach((value, key) => {
  if (callback(value, key)) relevant.set(key, value);
  });
  