show_anns function with unused variables

In the example [notebook ](https://github.com/facebookresearch/segment-anything/blob/main/notebooks/automatic_mask_generator_example.ipynb), in the `show_anns` function defination there are the variables 'polygons' and 'color' that assign as empty lists. They aren't applies or used in the function.
Why they are exist? It's maiking me think I'm forgetting something to apply in my code.

Open notebooks/automatic_mask_generator_example.ipynb and inspect the show_anns function, focusing on the polygons and color variables mentioned in the issue. Confirm whether they are referenced elsewhere in the function; done means the example no longer contains misleading unused variables or clearly explains their purpose.

Written by the indexing model from the issue text.