code: def start(self):
          
          if rospy.get_name() == '/unnamed':
              raise ValueError('PhoXi sensor must be run inside a ros node!')
  
          # Connect to the cameras
          if not self._connect_to_sensor():
              self._running = False
              return False
  
          # Set up subscribers for camera data
          self._color_im_sub = rospy.Subscriber('/phoxi_camera/texture', ImageMessage, self._color_im_callback)
          self._depth_im_sub = rospy.Subscriber('/phoxi_camera/depth_map', ImageMessage, self._depth_im_callback)
          self._normal_map_sub = rospy.Subscriber('/phoxi_camera/normal_map', ImageMessage, self._normal_map_callback)
  
          self._running = True
  
          return True
docs: Start the sensor.