Benchmark: timing 10000000 iterations of qr, string, string/o...
        qr: 11 wallclock secs (10.60 usr +  0.00 sys = 
          10.60 CPU) @ 943396.23/s (n=10000000)
    string: 11 wallclock secs (11.80 usr +  0.00 sys = 
          11.80 CPU) @ 847457.63/s (n=10000000)
  string/o:  7 wallclock secs ( 9.40 usr +  0.02 sys =  
           9.42 CP    U) @ 1061571.13/s (n=10000000)