Which python version this code base is targeting?

[photoszzt]

In one file:

cirrus/python/frontend/cirrus/cirrus/automate.py

Line 75 in e8ddc2e

LAMBDA_RUNTIME = "python3.6"

which hints that this repo targets python3
In the other file:

cirrus/python/frontend/cirrus/cirrus/lambdas/setup.sh

Line 3 in e8ddc2e

pip2 install mmh3

which hints that this repo targets python2
Is this repo supports both python version? Or only one of them?