As you can see in Figure 1, the original immutable stack (containing 10 elements) is unchanged after a call to the Pop() method. Rather, a new immutable stack is created with 9 elements.

LIFO stacks manage the stored data so that the last data stored in the stack is the first data removed from the stack. Use the stack to save the current values of (XLAST, YLAST) and (XLSTT, YLSTT) and ...