anchor.diff:              throw new ArgumentError("step must not be 0");
       }
   
  -    Iterator<int> get iterator {
  -        return new $RangeIterator(start, stop, step);
  -    }
  +    Iterator<int> get iterator => new $RangeIterator(start, stop, step);
   
       int get length {
           if ((step > 0 && start > stop) || (step < 0 && start < stop))
  
positive.code:     return new $PyDict(dict);
  }
  
  abs(n) {
      if (n < 0) return n * -1;
      else return n;
  }
  
  all(iterable) {
      for (var i in iterable) {
  
negative.code:                         return false;
                  }
                  return true;
              default: return false;
          }
      }
  
  