XOR

Pops two items from the stack, treats them as boolean values, ‘xors’ them, and pushes 0 or 1 back to the stack. If both items are TRUE, 0 is pushed to the stack. If both items are FALSE, 0 is pushed to the stack. If one item is TRUE and the other is FALSE, 1 is pushed to the stack.

if (1 xor (false))
    trace("1 xor false is true")
endif