Question: Rewrite the Scanner class in package ast5 so that it has an instance variable of type java.io.StreamTokenizer. The Scanner should use the StreamTokenizer to break down the expression into token substrings, which it then uses to form the Tokens to be returned by the get Next token () method. Simplify the Scanner class as much as possible (i.e., try to utilize Stream tokenizer to do as much of the work as possible).