module Lock_file: Lock_file
val create : ?message:string ->
       ?close_on_exec:bool ->
       ?unlink_on_exit:bool -> string -> bool Import.Deferred.t
create ?message path tries to create a file at path containing the text message,
    pid if none provided.  It returns true on success, false on failure.  Note: there is
    no way to release the lock or the fd created inside!  It will only be released when
    the process dies.
val create_exn : ?message:string ->
       ?close_on_exec:bool ->
       ?unlink_on_exit:bool -> string -> unit Import.Deferred.t
create_exn ?message path is like create except that it throws an exception on
    failure instead of returning a boolean value
val waiting_create : ?message:string ->
       ?close_on_exec:bool ->
       ?unlink_on_exit:bool -> string -> unit Import.Deferred.t
wait_create ~path ~message becomes determined when the file at 
path gets locked.
    Equivalent to 
Core.Std.Lock_file.blocking_create.
 
val is_locked : string -> bool Import.Deferred.t
is_locked path returns true when the file at path exists and is locked, false
    otherwise.