Python beginner tip 1

gistfile1.txt

#!/usr/bin/python3
#
# Instead of just typing:

print("hello world")


# Do this (main is a placeholder; the actual thing it does is better):

def main():
  print("hello world")

  
# This will only be called if you run this file directly. 
# If it is for instance imported by another file, it will not run this:

if __name__ == "__main__":
  main()