my $n_tests       = 1_000_000;

    my $error= 1+ int rand 5;
    my $A      = rand64($n_err + 1 + rand 50);
    my $B      = rand64($n_err + 1 + rand 50);
    my $prefix = rand64($n_err + 1 + rand 20);

> Took: 2.20354223251343 sec