Our linked-list implementation (Fig. 21.3) used both a firstNode and a lastNode. The lastNode was useful for the insertAtBack and removeFrom- Back methods of the List class. The insertAtBack method corresponds to the enqueue method of the Queue class. Rewrite the List class so that it does not use a lastNode. Thus, any operations on the tail of a list must begin searching the list from the front. Does this affect our implementation of the Queue class (Fig. 21.11)?