How do I program a static layer?

This was not explained in the modding tree’s docs. I’m confused as to how I make the cost formula. Also, it won’t unlock, but I’m sure that is connected to the requirement. If you know anything, please help me.

type: “static”,
exponent: // any exponent, so long it’s balanced’’’

Unlocking will be found in layerShown() and startData()

Thank you. It didn’t explain how to code the cost scaling so this is really helpful.