In ::math::bignum, most of the comparison functions
(except for iszero) require two bignums as inputs.
However, there are many cases where the comparison is
between 0 and some number.
Right now, you need to make a bignum of 0 to do the
comparison. It should be possible to special case the
comparisons so that the comparison is against the
literal 0 would be permitted.
Another possibility would be to predefine two useful
numbers as bignum constants: 0 and 1. With those two
predefined, a lot of tests would be able to avoid
having to create them. (Other powers of two (2^1, 2^2,
2^3, ...2^64) would be potentially useful as well, but
perhaps less worth the overhead.)