$ pm_1170300_bench_undef_hash_value.pl; pm_1170300_bench_undef_hash_value.pl; pm_1170300_bench_undef_hash_value.pl; pm_1170300_bench_undef_hash_value.pl; pm_1170300_bench_undef_hash_value.pl
        Rate a_inc val_0 undef val42 val_1
a_inc 4129/s    --   -1%   -1%   -1%   -2%
val_0 4151/s    1%    --   -1%   -1%   -1%
undef 4188/s    1%    1%    --   -0%   -0%
val42 4191/s    2%    1%    0%    --   -0%
val_1 4198/s    2%    1%    0%    0%    --
        Rate a_inc undef val_1 val42 val_0
a_inc 4193/s    --   -2%   -2%   -2%   -2%
undef 4272/s    2%    --   -0%   -0%   -0%
val_1 4275/s    2%    0%    --   -0%   -0%
val42 4290/s    2%    0%    0%    --   -0%
val_0 4290/s    2%    0%    0%    0%    --
        Rate a_inc val_0 val_1 undef val42
a_inc 4228/s    --   -1%   -1%   -1%   -2%
val_0 4277/s    1%    --   -0%   -0%   -1%
val_1 4292/s    2%    0%    --    0%   -0%
undef 4292/s    2%    0%    0%    --   -0%
val42 4301/s    2%    1%    0%    0%    --
        Rate a_inc val_0 val_1 val42 undef
a_inc 4174/s    --   -1%   -2%   -2%   -2%
val_0 4207/s    1%    --   -1%   -1%   -1%
val_1 4239/s    2%    1%    --   -0%   -0%
val42 4243/s    2%    1%    0%    --   -0%
undef 4243/s    2%    1%    0%    0%    --
        Rate a_inc val_0 val_1 undef val42
a_inc 4239/s    --   -1%   -2%   -2%   -2%
val_0 4279/s    1%    --   -1%   -1%   -1%
val_1 4305/s    2%    1%    --   -0%   -0%
undef 4308/s    2%    1%    0%    --   -0%
val42 4316/s    2%    1%    0%    0%    --