In preparing my email, I was looking for a way to identify a ufunc, other
than `isinstance`, since `np.vectorize` and `nb.vectorize` make objects
that behave like ufuncs (even obeying NEP 13 semantics, checking for
`__array_ufunc__`), but they don't inherit from the `np.ufunc` type. I was
thinking
Stack is not a generalized ufunc.
It may behave similar to one in many ways, but implementation wise has
nothing to do with ufuncs.
Also ufuncs do not support an arbitrary number of operands.
`vectorize` can indeed mimic generalized ufuncs, but (unfortunately)
doesn't create them as such currentl
