#### socket_acceptor_service::async_accept

Start an asynchronous accept.

    template<
        typename Protocol1,
        typename SocketService,
        typename AcceptHandler>
    void-or-deduced async_accept(
        implementation_type & impl,
        basic_socket< Protocol1, SocketService > & peer,
        endpoint_type * peer_endpoint,
        AcceptHandler handler,
        typename enable_if< is_convertible< Protocol, Protocol1 >::value >::type *  = 0);