Create the following: The superclass Calculator that contains:
(give a proper visibility for class memebers)
a double instance variable called accumulator that contains the current value of the calculator.
The subclass, CalculatorWithMemory, that contains:
a double instance variable, memory, initialized to 0
a method, save, that assigns the value of accumulator to memory
a method, recall, that assigns the value of memory to accumulator
a method, clearMemory, that assigns zero to memory
a method, getMemory, that returns the value stored in memory

Test your CalculatorWithMemory class by creating an object and calling its methods in the Main class.