We can design and build a postfix calculator that can be used to perform simple arithmetic operations. The calculator consists of a single storage component that consists of an operand stack. The operations performed by the stack always use the top two values of the stack and store the result back on the top of the stack. Implement the operations of the Postfix Calculator ADT as defined here:.
* PostfixCalculator(): Creates a new postfix calculator with an empty operand stack.
* value( x ): Pushes the given operand x onto the top of the stack.
* result(): Returns an alias to the value currently on top of the stack. If the stack is empty, None is returned.
* clear(): Clears the entire contents of the stack.
* clearLast(): Removes the top entry from the stack and discards it.
* compute( op ): Removes the top two values from the stack and applies the given operation on those values. The first value removed from the stack is the righthand side operand and the second is the lefthand side operand. The result of the operation is pushed back onto the stack. The operation is specified as a string containing one of the operators + - * / **.