Benchmark: timing 1000000 iterations of eq, index, regex...
        eq:  1 wallclock secs ( 0.89 usr +  0.00 sys =  0.89 CPU) @ 1123595.51/s (n=1000000)
     index:  2 wallclock secs ( 1.65 usr +  0.00 sys =  1.65 CPU) @ 606060.61/s (n=1000000)
     regex:  2 wallclock secs ( 1.63 usr +  0.00 sys =  1.63 CPU) @ 613496.93/s (n=1000000)
           Rate index regex    eq
index  606061/s    --   -1%  -46%
regex  613497/s    1%    --  -45%
eq    1123596/s   85%   83%    --