code: def _dice_loss(self, inputs, targets, num_gts):
      inputs = F.sigmoid(inputs)
      inputs = inputs.flatten(1)
      targets = targets.flatten(1)
      numerator = 2 * (inputs * targets).sum(1)
      denominator = inputs.sum(-1) + targets.sum(-1)
      loss = 1 - (numerator + 1) / (denominator + 1)
      return loss.sum() / num_gts
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from ppdet.core.workspace import register
  from .iou_loss import GIoULoss
  from ..transformers import bbox_cxcywh_to_xyxy, sigmoid_focal_loss, varifocal_loss_with_logits
  from ..bbox_utils import bbox_iou
label_desc: Use image node_id 5 for calling the DETRLoss obj's underlying member method code with example usage: obj._dice_loss(inputs, targets, num_gts) and returns: unknown