John Stilley

There is a PR [currently open](https://github.com/terrapower/armi/pull/1090) that should greatly simplify this ticket. Essentially, the EOL will be correctly in place now, and differentiable from the last cycle, node combination. Now...

@keckler Can we close this ticket now?

We talked about this ticket as a group and the approach we think is cleanest is to move `setNumberDensities()` from `ArmiObject` to `Component`. (This might mean also moving `setNumberDensity()` over....

I have two thoughts on this PR: 1. The goal of "Example 2" was to show people the fewest possible lines of Python code needed to plot the thing maze....

> I am not sure this is worth doing. The Python org is pushing so hard for everyone to abandon the old `setup.py` approach and move to the new `pyproject.toml`...

That seem like a cool idea, sure. I should probably read the docs there and play with the two, just to make sure. But from your description, I agree that...

I also have more information on virtual environments here that we are free to use: https://antineutrino.net/2023/04/11/python-venvs

> I have a module Are you saying the problem is resolved? If not, can you give me two things: 1. **Information about your system**: OS version, Python version 2....

@drewj-usnctech Just to be sure. This features is meant to support "custom isotopics" in our blueprints: https://github.com/terrapower/armi/blob/7b26f79ac8c58b0477b0d7fa384b363d10fa9406/armi/reactor/blueprints/tests/test_componentBlueprint.py#L290-L293 Is that how you're using the `Custom(Material)` class?

I think a lot of ARMI PRs are failing right now because the unit tests aren't cleaning up after themselves. In particular, after all the tests are run, a file...