Benchmark: timing 500000 iterations of regexp, substr...
	    regexp: 11 wallclock secs (10.16 usr +  0.00 sys = 10.16 CPU) @ 49236.83/s (n=500000)
	    substr:  1 wallclock secs ( 0.90 usr +  0.00 sys =  0.90 CPU) @ 554938.96/s (n=500000)