static if(!(__traits(compiles, expectType!(ab[0]), expectType!(ab[1]))))
static if(!__traits(compiles, expectType!(ab[0])) && !__traits(compiles, expectType!(ab[1])) && __traits(compiles, expectBool!(ab[0] == ab[1])))
static if(!__traits(compiles, &ab[0]) || !__traits(compiles, &ab[1]))