/* USB.find_busses */
static VALUE
rusb_find_busses(VALUE cUSB)
{
  st_foreach(bus_objects, revoke_data_i, 0);
  st_foreach(device_objects, revoke_data_i, 0);
  st_foreach(config_descriptor_objects, revoke_data_i, 0);
  st_foreach(interface_objects, revoke_data_i, 0);
  st_foreach(interface_descriptor_objects, revoke_data_i, 0);
  st_foreach(endpoint_descriptor_objects, revoke_data_i, 0);
  return INT2NUM(usb_find_busses());
}