RealFunction

static int f(long x)
{
	return cast(int)((x >> 32) ^ (x & ((1UL << 32) - 1)));
}
static assert (is (RealFunction!f : Function!(long, int)));
static assert (is (RealFunction!(f, int, int) : Function!(int, int)));
static assert (is (RealFunction!(f, int, long) : Function!(int, long)));
static assert (is (RealFunction!(f, long, long) : Function!(long, long)));