In Python, how can I test if I'm in Google App Engine SDK?
Update on October 2020: 
I tried using os.environ["SERVER_SOFTWARE"] and os.environ["APPENGINE_RUNTIME"] but both didn't work so I just logged all keys from the results from os.environ.
In these keys, there was GAE_RUNTIME which I used to check if I was in the local environment or cloud environment. 
The exact key might change or you could add your own in app.yaml but the point is, log os.environ, perhaps by adding to a list in a test webpage, and use its results to check your environment.
Whilst developing I want to handle some things slight differently than I will when I eventually upload to the Google servers. 
Is there a quick test that I can do to find out if I'm in the SDK or live?