Organizing files in Sage Cloud/modules

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I am working in sage cloud, in a worksheet (sagews). I wrote some classes and methods so far and I wish to keep them separated from my new code/organize my projects in files that I can import from.

I want something like

file Resources.(.py? .sage? .sagews?) with classes Foo, Foo2, Foo3

and to use this in a new spreadsheet: from Resources import Foo2

While this seems like a basic question, the only thing I could discover on this topic was a similar unanswered question: http://ask.sagemath.org/question/2604...

How do I do this? How do I split a project in several files(modules?) that I could import from?