Stack
Stack collection (LIFO discipline).
Minimal LIFO (last in first out) implementation, as a class.
See library Deque for mixed LIFO/FIFO behavior.
class Stack<T>
Function push
func push(x : T)
Push an element on the top of the stack.
Function isEmpty
func isEmpty() : Bool
True when the stack is empty.
Function peek
func peek() : ?T
Return and retain the top element, or return null.
Function pop
func pop() : ?T
Remove and return the top element, or return null.