Improve the hash table implementation of Program 5.2: a. Double the size of the array when the average bucket length grows larger than 2 (so table is now ref(array)). To double an array, allocate a bigger one and rehash the contents of the old array; then discard the old array. b. Allow for more than one table to be in use by making the table a parameter to insert and lookup. c. Hide the representation of the table type inside an abstraction module, so that clients are not tempted to manipulate