#!/usr/bin/python

This is sometimes what you want, but it will always look at this exact path, and won't play nicely with virtualenv/conda.

    #!/usr/bin/env python

This works - it will use Python found in $PATH. Unfortunately you can't add any more parameters to the interpreter.

The contraption I wrote allows adding arbitrary parameters - I was burnt one too many times by Python silently buffering my debug messages, so I use it to always add "-u".