In computing, a shebang (also called a hashing, hashpling, poundbang, or crunching) refers to the characters “#!” when they are the first two characters in an interpreter directive as the first line of a text file. In a Unix-like operating system, the program loader takes the presence of these two characters as an indication that the file is a script, and tries to execute that script using the interpreter specified by the rest of the first line in the file.

If you need python 2.7
#!/usr/bin/env python2.7

If you need python 3
#!/usr/bin/env python3

Reference

https://stackoverflow.com/questions/2429511/why-do-people-write-the-usr-bin-env-python-shebang-on-the-first-line-of-a-pyt