code: def pop(stack, op_id):
    
    if __debug__:
      pushed_value, pushed_op_id = stack.pop()
      assert pushed_op_id == op_id, 'Wanted %s, got %s' % (op_id, pushed_op_id)
    else:
      pushed_value = stack.pop()
    return pushed_value
docs: Pop a value from the stack (i.e. read it from the tape).
  
    Args:
      stack: The stack to pop from.
      op_id: A unique variable that is also passed into the matching push.
          Allows optimization passes to track pairs of pushes and pops.
  
    Returns:
      The last value.