code: def __call__(
      self,
      rpn_rois,
      rpn_rois_num,
      inputs,
      stage=0,
      is_cascade=False,
      add_gt_as_proposals=True,
  ):
      gt_classes = inputs["gt_class"]
      gt_boxes = inputs["gt_bbox"]
      is_crowd = inputs.get("is_crowd", None)
      # rois, tgt_labels, tgt_bboxes, tgt_gt_inds
      # new_rois_num
      outs = generate_proposal_target(
          rpn_rois,
          gt_classes,
          gt_boxes,
          self.batch_size_per_im,
          self.fg_fraction,
          self.fg_thresh,
          self.bg_thresh,
          self.num_classes,
          self.ignore_thresh,
          is_crowd,
          self.use_random,
          is_cascade,
          self.cascade_iou[stage],
          self.assign_on_cpu,
          add_gt_as_proposals,
      )
      rois = outs[0]
      rois_num = outs[-1]
      # tgt_labels, tgt_bboxes, tgt_gt_inds
      targets = outs[1:4]
      return rois, rois_num, targets
  
imports: import sys
  import paddle
  from ppdet.core.workspace import register, serializable
  from .target import rpn_anchor_target, generate_proposal_target, generate_mask_target, libra_generate_proposal_target
  import numpy
label_desc: Use image node_id 2 for calling the BBoxAssigner obj's underlying member method code with example usage: obj.__call__(rpn_rois, rpn_rois_num, inputs, stage, is_cascade, add_gt_as_proposals) and returns: rois,  rois_num,  targets