I'm testing my (binomial n p) random variate generator, and started with
edge cases.

Some random variate generators make sense when p=0 or p=1 (e.g.,
binomial, bernoulli) and some don't (perhaps geometric).

I'm going to try to ensure that make-binomial-generator does "the right
thing" in edge cases, I don't think I can check all the rest.

Brad