Docs: Add missing 'import sys' to Canvas Creation tutorial

[kimssammwu]

The example code in the Canvas Creation section of the tutorial requires the sys module to run correctly, but the import sys statement was missing.

This change adds the import sys to resolve the error.

[HinTak]

Can you explain where the error is triggered? I don't see the use of sys.* nearby.

[kimssammwu]

Can you explain where the error is triggered? I don't see the use of sys.* nearby.

Hello, thank you for reviewing the Pull Request.

I apologize for the confusion; I've identified the precise reason why the changes were not initially visible.

The issue was a formatting mistake in the file. I mistakenly committed the file without a blank line immediately following the .. code-block:: python directive. This error prevented the code block from rendering correctly when the documentation was built.

The original purpose of the PR was to fix the Code Omission Issue for the missing sys package, which was necessary because sys.platform was being used in two locations:

• Line 13 of Canvas Creation#gpu
• Line 12 of Canvas Creation#opengl-window

I have now resolved both the document formatting error and the core code issue.

[HinTak]

Okay, my fault : the if sys.platform.startswith("darwin") lines (which I added a while ago) clearly need import sys. I'd prefer you don't change the white space in the 2nd block though (you seems to have added a tab or a bunch of spaces).

[kimssammwu]

I have made the requested change!

[HinTak]

The CI segfault is #350 . We'll see about fixing that at some point.