There is no open-source / free decompiler for Python - just a “disassembler” (see dis-module in stdlib). Returning from the Python Stack-VM assembly (which is stored in .pyc files) to Python working code is basically simple, since the general structure of the code is preserved even when using -O.
(.. .pyc-s [pre 2.3] -), . @FabioZadrozny, Python >= 2.5 .pyc-s, , , , /.