title: activate another conda env inside python code
body: <p>I need to use both python2.7 and python3.6 for a task. I used conda to create two python envs. I know how to use a shell script to control the code running and switch between different envs. Say I need to run python2.7 code first, then I run python 3.6. My question is could I first run python 2.7 code, and then in the python 2.7 code, I directly activate the python3.6 conda env, and run the python 3.6 code? </p>