Two more last minute changes from PEPs

I'm two more chnages I've gleaned from Python PEPs.

The first is a small change but very important.  It is the use of a main_()
function in modules like C language does.  This replaces the old convention
of testing to see if the module has been loaded as main.  This is not only
cleaner, but it allows a script to load a module and run it.