[IronPython] How can I exit from Python Script File?

[Thomas Gagne]

My question is simpler,  how do I exit a regular script?

If ARGV.length != 1
     puts "usage:...."
     Process.exit
end

I get an error calling Process.exit (private member)
Process.Exit (method does not exist)
sys.Exit (undefined method 'sys' for main:Object)

How do I quit my script?