module Mutex:sig..end
Locks for mutual exclusion.
Mutexes (mutual-exclusion locks) are used to implement critical sections
   and protect shared mutable data structures against concurrent accesses.
   The typical use is (if m is the mutex associated with the data structure
   D):
     Mutex.lock m;
     (* Critical section that operates over D *);
     Mutex.unlock m
   type 
The type of mutexes.
val create : unit -> tReturn a new mutex.
val lock : t -> unitLock the given mutex. Only one thread can have the mutex locked at any time. A thread that attempts to lock a mutex already locked by another thread will suspend until the other thread unlocks the mutex.
val try_lock : t -> boolSame as Mutex.lock, but does not suspend the calling thread if
   the mutex is already locked: just return false immediately
   in that case. If the mutex is unlocked, lock it and
   return true.
val unlock : t -> unitUnlock the given mutex. Other threads suspended trying to lock the mutex will restart.