pub unsafe extern "C" fn g_dbus_connection_call(
    connection: *mut GDBusConnection,
    bus_name: *const c_char,
    object_path: *const c_char,
    interface_name: *const c_char,
    method_name: *const c_char,
    parameters: *mut GVariant,
    reply_type: *const GVariantType,
    flags: GDBusCallFlags,
    timeout_msec: c_int,
    cancellable: *mut GCancellable,
    callback: GAsyncReadyCallback,
    user_data: gpointer
)