Rate  using_x assign_undef assign_length x_with_value    assign
using_x       35870/s       --          -1%           -1%          -2%       -4%
assign_undef  36133/s       1%           --           -0%          -1%       -4%
assign_length 36298/s       1%           0%            --          -1%       -3%
x_with_value  36540/s       2%           1%            1%           --       -3%
assign        37497/s       5%           4%            3%           3%        --