code: function() {
           this._nextCalled = true;
           if(this._collection.size() > 0) {
               if(this._hasNextCalled) {
                   this._hasNextCalled = false;
                   this._pos --;
               }
  
               this._pos ++;
               this._nextElement = this._collection.getAll()[this._pos];
  
               if(this._nextElement !== undefined) {
                   return this._nextElement;
               } else {
                   throw new Error("No such element.");
               }
           }
       }
docs: Returns the next element in the iteration.
  @throws Error