1041. Robot Bounded In Circle - Explanation

class Solution:
    def isRobotBounded(self, instructions: str) -> bool:
        dirX, dirY = 0, 1
        x, y = 0, 0

        for d in instructions:
            if d == "G":
                x, y = x + dirX, y + dirY
            elif d == "L":
                dirX, dirY = -dirY, dirX
            else:
                dirX, dirY = dirY, -dirX

        return (x, y) == (0, 0) or (dirX, dirY) != (0, 1)