The toy robot problem, using python decorators

toy_robot.py

def pos_safe(fn):
    def wrapper(self):
        old = self._pos.copy()
        fn(self)
        for i in range(2):
            if not (0 <= self._pos[i] <= self.bounds[i]):
                self._pos = old
                raise ValueError("Robot shall not pass!")
        self.curpos()
           
    return wrapper

class Robot:
    _pos = [0, 0]
    
    def __init__(self, bounds=(5, 5)):
        self.bounds = bounds
        
    def curpos(self):
        print("Robot positon:", self._pos)  
        
    @pos_safe
    def right(self):
        self._pos[0] += 1
        
    @pos_safe
    def left(self):
        self._pos[0] -= 1
        
    @pos_safe
    def up(self):
        self._pos[1] += 1
        
    @pos_safe
    def down(self):
        self._pos[1] -= 1