cost helper function

[claytonpbarrows]

Background

We need a helper function to give users an understanding of how cost data is being treated in PSI formulations. The challenge is that the ultimate treatment of cost data is dependent on the structure of the data along with the formulation itself.

Approach

Create a helper function that takes a device and a DeviceModel and provides the "resulting cost" (that's poorly defined) that's used in PSI.

Open questions

What is a useful "resulting cost" output