def test_stack_push_pop():
stk = Stack()
stk.push(2)
stk.push(3)
assert stk.peek() == 3
assert stk.pop() == 3
assert stk.peek() == 2
assert stk.pop() == 2
def test_stack_swap():
stk = Stack()
stk.push(2)
stk.push(3)
stk.swap()
assert stk.peek() == 2
assert stk.pop() == 2
assert stk.peek() == 3
assert stk.pop() == 3
def test_executor_g():
lines = [['>', 'v'], ['<', '^']]
fld = Field(2, 2, lines)
stk = Stack()
crt = Caret(stk, fld)
stk.push(1)
stk.push(0)
exec_g(crt)
assert stk.peek() == ord('v')