# Objective
I was wrong about how RPITIT works when I wrote this stuff initially,
and in order to actually give people access to all the traits
implemented by the output (e.g. Debug and so on) it's important to
expose the real output type, even if it makes the trait uglier and less
comprehensible. (☹️)
## Solution
Expose the curve output type of the `CurveWithDerivative` trait and its
double-derivative companion. I also added a bunch of trait derives to
`WithDerivative<T>`, since I think that was just an oversight.
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