Break Entrance and Exit

Now you should have a full grid drawn on the screen, like this.

Now it's time to start removing ("breaking") some walls so that we have an actual maze. We'll start with the entrance and exit.

Assignment

Create a new method in the Maze class called __break_entrance_and_exit(self). This method should:
- Remove the top wall of the top-left cell by setting has_top_wall = False (the entrance)
- Remove the bottom wall of the bottom-right cell (the exit)
- Call self._draw_cell() after each removal to update the display
Add a unit test for the __break_entrance_and_exit() method.

If you run your code graphically, it won't appear to actually remove any walls. That's because they were already drawn to the canvas, and removing the wall in memory doesn't update the canvas. Let's fix that.

Update the draw() method in your Cell class to draw a "white" or "#d9d9d9" line (the color of the background depending on your OS) for walls that don't exist instead of doing nothing. Now when you run your code it should remove the entrance and exit walls visually.