The Python dis module allows you to disassemble bytecode from the same version
of Python that you are running on. But what about bytecode from different
versions?

That's what this package is for. It can "marshal load" Python bytecodes from
different versions of Python. The command-line routine pydisasm will show
disassembly output using Python 3.6 disassembly conventions.

Also, if you need to modfiy and write bytecode, the routines here can be of
help. There are routines to pack and unpack the read-only tuples in Python's
Code type. For interoperability between Python 2 and 3 we provide our own
versions of the Code type, and we provide routines to reduce the tedium in
writing a bytecode file.

This package also has an extensive knowledge of Python bytecode magic numbers,
including Pypy and others, and how to translate from sys.sys_info major, minor,
and release numbers to the corresponding magic value.

So If you want to write a cross-version assembler, or a bytecode-level
optimizer this package may also be useful. In addition to the kinds of
instruction categorization that dis offers, we have additional categories for
things that would be useful in such a bytecode optimizer.