Chrome OS RMA shim - Missing modules?

[AJ Quinn]

Hello all,

I am relatively new to Chromium OS development and I am having a fair bit of trouble running the toolset found here: 

https://chromium.googlesource.com/chromiumos/platform/factory/+/HEAD/setup/RMA_SHIM.md#Get-the-tool

Particularly when trying to run "py/tools/image_tool_rma_unittest.py" I get an error saying this:

from cros.factory.tools import image_tool

ModuleNotFoundError: No module named 'cros'

I get that I am missing a module but the questions are: where do I get it? Or is the factory directory in the wrong place?

Thank you

AJ