Lightweight console/IDE for Python?

Question

I often use ipython (or the regular python shell) to test python code snippets while coding, and it's been very useful. One shortcoming of this, though, is that if I want to test a multi-line segment of code, or want to write multiple lines of code before running, it isn't very convenient to have to do it "line by line". And even going back to change some of the lines is cumbersome because you have to re-type all the code that comes after it.

I'm playing with Groovy right now and I find that it has an excellent solution to this problem: the Groovy Console. You just write all the code you want, it's just like a regular editor; and then you hit run Ctrl+R (Cmd+R actually since I'm on a Mac) and it runs everything at once. If you want to change something (e.g. if there are errors), then that's easy too -- just change it and Ctrl+R again.

Is there an equivalent of this available for python? Or do you have any recommendations on a way to achieve similar behavior? I could just create a new file, save it, and then python <filename>.py from the shell. But that's just too many steps and would be cumbersome. Eclipse may be an option, but it's too heavyweight. I'm really looking for something lightweight that I can just spin up when I want to test something and then get rid of it just as quickly.

I'd be interested to hear any ideas/suggestions!

Thanks