How do I convert a notebook to a python script?

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I'm asking this because I'm starting a project and Sage seems like a very good platform to do some prototyping.

Better yet, it might be a great way to use the code that results from my prototyping directly has the final version as well.

But for that to work with a minimal of hardship though, a few things would be usefull:

1. A way to grab the code content of a notebook and generate an independent python script or function

2. A list of libraries, with version, that every sage version uses.

3. An instalable library version of sage that could be imported from the script

4. Anything else that I'm missing and you know sage can do to help in this task

I'm not asking for a completely automatic way to do this, just for resources/scripts or general advices about how to do it.

I'm also just starting to look into sage so, don't assume to much on what I may know. ;)

Thanks.