code: def detector(detector_type):
          
          if detector_type == 'point_cloud_box':
              return PointCloudBoxDetector()
          elif detector_type == 'rgbd_foreground_mask_query':
              return RgbdForegroundMaskQueryImageDetector()
          elif detector_type == 'rgbd_foreground_mask':
              return RgbdForegroundMaskDetector()
          raise ValueError('Detector type %s not understood' %(detector_type))
docs: Returns a detector of the specified type.