/// Has a [norm](https://en.wikipedia.org/wiki/Norm_(mathematics)) and
/// [unit](https://en.wikipedia.org/wiki/Unit_(ring_theory))
///
/// For our purposes, the units are expected to have norm `1`.
/// However, we do **not** expect `x = |x| unit(x)`.
/// For example, for a normal integer you would have `x = |x| unit(x)` but
/// for a p-adic integer you would have `x = p^(val(x)) unit(x) = (|x|_p)^(-1) unit(x)`.