Benchmark: timing 100000 iterations of b, f...
         b: 83 wallclock secs (67.82 usr + 14.38 sys = 82.20 CPU) @ 1216.55/s (n=100000)
         f: 80 wallclock secs (65.86 usr + 13.95 sys = 79.81 CPU) @ 1252.98/s (n=100000)