In reply to @general_rishkin "I hope some one": Yeah, as @enthus1ast. said you
can define a fully custom unit system. But if you just want to extend the
default SI (plus additions) system for units, you just use the `defUnit`
macro. If you cant to add a new quantity like `Intensity` there is currently
not a way to add that without a custom unit system or a PR to add it here:https
://github.com/SciNim/Unchained/blob/master/src/unchained/si_units.nim#L8-L40

Note that quantities are really only a convenience tool to use for generic procs
so that you can write `proc[L: Length, F: Force](x: L, f: F)` etc. So most
likely `defUnit` is all you want. Also feel free to open an issue or ping me
again!