SilcUInt16 silc_client_command_send(SilcClient client,
                                        SilcClientConnection conn,
                                        SilcCommand command,
                                        SilcClientCommandReply reply,
                                        void *reply_context,
                                        SilcUInt32 argc, ...);

    Generic function to send any command.  The arguments must be given
    already encoded into correct format and in correct order. If application
    wants to perform the commands by itself, it can do so and send the data
    directly to the server using this function.  If application is using
    the silc_client_command_call, this function is usually not used.
    Programmer should get familiar with the SILC protocol commands
    specification when using this function, as the arguments needs to
    be encoded as specified in the protocol.

    The variable arguments are a set of { type, data, data_length },
    and the `argc' is the number of these sets.

    The `reply' callback must be provided, and it is called when the
    command reply is received from the server.  Note that, when using this
    function the default `command_reply' client operation callback will not
    be called when reply is received.

    Returns command identifier for this sent command.  It can be used
    to additionally attach to the command reply using the function
    silc_client_command_pending, if needed.  Returns 0 on error.

    silc_client_command_send(client, conn, SILC_COMMAND_WHOIS,
                             my_whois_command_reply, cmd_ctx,
                             1, 1, nickname, strlen(nickname));