s/iter for2  map  for
for2   2.70   --  -1%  -1%
map    2.68   1%   --  -0%
for    2.67   1%   0%   --
Benchmark: running for, for2, map for at least 60 CPU seconds...
       for: 61 wallclock secs (61.37 usr +  0.02 sys = 61.39 CPU) @  0.37/s (n=23)
      for2: 61 wallclock secs (61.37 usr +  0.03 sys = 61.40 CPU) @  0.37/s (n=23)
       map: 62 wallclock secs (61.48 usr +  0.03 sys = 61.51 CPU) @  0.37/s (n=23)