I'm not especially proud of the code : it's messy, took a long time
and could probably be vastly improved.
I could have used the intersperse iterator method but it's currently in
nightly only. Maybe another way of parsing the string would have prevented
the need ?
Solved with threads, slower by 20-30% for this workload apparently.
Might be because it is the same solution, juste using a new thread for each test
instead of one thread. Early exit does not seem to improve things, as the threads
complete very quickly.
