anchor.diff:      }
     }
   
  -  Iterable map(f(E element)) {
  -    return new MappedListIterable(this, f);
  +  Iterable<T> map<T>(T f(E element)) {
  +    return new MappedListIterable<E, T>(this, f);
     }
   
     String join([String separator = ""]) {
  
positive.code:     return new WhereIterable<E>(this, f);
    }
  
    Iterable expand(Iterable f(E element)) {
      return new ExpandIterable<E, dynamic>(this, f);
    }
  
    void addAll(Iterable<E> collection) {
  
negative.code:     return value;
    }
  
    T fold<T>(T initialValue, T combine(T previousValue, E element)) {
      var value = initialValue;
      int length = this.length;
      for (int i = 0; i < length; i++) {
  