Concur.v: prove the not-terribly-interesting [write_to_file_works_easy] theorem
Concur.v: prove the not-terribly-interesting [write_to_file_works_easy] theorem

since there are no other threads running, this is just a matter of
repeatedly destructing.

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl