Newbie edit/compile/run cycle question

[MartinRinehart at gmail.com]

I'm a java guy used to the effective edit/run cycle you get with a
good IDE.

Today I'm writing my first Python, but can't seem to find the way to
use Python's inherent edit/run cycle.

I edit my source, import it into Python, run it. Fine. Then I edit
again, but the next import doesn't notice that a new compile is
needed. I'm making a little progress (very little) by exiting/
reentering Python after each edit. Ugh.

What don't I know that I should know to just edit/run, preferably at
the tap of a function key?