class direct_acceptor :?close_on_shutdown:bool -> ?preclose:unit -> unit -> Unix.file_descr -> Unixqueue.event_system ->server_endpoint_acceptor
server_endpoint_acceptor for sockets and Win32
    named pipes. For sockets, the passed descriptor must be the master
    socket. For Win32 named pipes, the passed descriptor must be the
    proxy descriptor of the pipe server..