We should try and reduce the content in the header file, as it is exposed to anything that includes it.

• mt_continue_should_break() moves into compressor.c
• The decompress_type enum moves into decompressor.c
• Replace #pragma once (not used for any other modules or non-vendored code) with guard defines
• Use angle-bracket includes for z{std,dict}.h
• Add a zstddict.h header file to contain the definition of the ZstdDict struct
• Move the ZstdCompressor struct to compressor.c (likewise for decompressor)
• Make PyModuleDef _zstdmodule static

A

• Issue: Implement PEP 784 - Adding Zstandard to the Python standard library #132983