code: def _mask_postprocess(self, mask_pred, score_pred, index):
      mask_score = F.sigmoid(paddle.gather_nd(mask_pred, index))
      mask_pred = (mask_score > self.mask_threshold).astype(
          mask_score.dtype
      )
      if self.use_avg_mask_score:
          avg_mask_score = (mask_pred * mask_score).sum([-2, -1]) / (
              mask_pred.sum([-2, -1]) + 1e-6
          )
          score_pred *= avg_mask_score
  
      return mask_pred[0].astype("int32"), score_pred
  
imports: import numpy
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from ppdet.core.workspace import register
  from ppdet.modeling.bbox_utils import nonempty_bbox
  from .transformers import bbox_cxcywh_to_xyxy
label_desc: Use image node_id 2 for calling the DETRPostProcess obj's underlying member method code with example usage: obj._mask_postprocess(mask_pred, score_pred, index) and returns: mask_pred,  score_pred