Run code only if script called from the command line

It is common to put this at the bottom of your script:

if __FILE__==$0
  # this will only run if the script was the main, not load'd or require'd
end

Because I like to see the main action at the top of my file, I usually put a def run! as the first method in the file and then end the file with:

run! if __FILE__==$0