How to combine two versions of the python3

Question

I need some advice.

I have a custom module requires version Python3.5 during installation or later versions. (no critical for run my script)

My script will simultaneously use "some_decoder.pyc" file which was compiled under Python3.3 (legacy) and need this version for run. (critical for run)

How I can to solve this problem if I use Linux and virtualenv?

I have one idea in two steps:

1. I install basic module under global environment (Python3.5).
2. I will create an environment which inherit basic modules but use python3.3 (in Windows I was able to do so)

But I hope that this problem can be solved in a different way, or redirect me where this problem was solved.