anchor.diff:      return false;
     }
   
  -  Enumerable select(Func1 f) {
  +  Enumerable select(Func1<T, Object> f) {
       requireArgumentNotNull(f, 'f');
       return new _FuncEnumerable(this, (s) => new _SelectIterator(s, f));
     }
  
positive.code:    * Returns true if one element of this collection satisfies the
     * predicate [f]. Returns false otherwise.
     */
    bool some(bool f(T element)) {
      requireArgumentNotNull(f, 'f');
      for (final e in this) {
        if(f(e)) {
  
negative.code:    * Returns true if every elements of this collection satisify the
     * predicate [f]. Returns false otherwise.
     */
    bool every(Func1<T, bool> f) {
      requireArgumentNotNull(f, 'f');
      for (final e in this) {
        if(!f(e)) {
  