How to edit obj part textures

[JisuHann]

Hi, thanks for your splendid work.

I would like to modify the specific obj's part texture, such as the a top drawer from the entire drawer obj.
From this line in pyrep, it seems to be possible to modify by code line, not modifying the obj texture itself. Is there any guidance or example code of this?

Thank you!

[KzZheng]

Sorry, I didn't modify the part texture by code before.