<s>[INST] What is __init__.py for? What is __init__.py for in a Python source directory?
 [/INST] It's a part of a package. Here's the documentation.

The __init__.py files are required to make Python treat the directories as containing packages; this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later (deeper) on the module search path. In the simplest case, __init__.py can just be an empty file, but it can also execute initialization code for the package or set the __all__ variable, described later.

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