code: def forward(self, feats, targets=None, aux_pred=None):
      assert len(feats) == len(
          self.fpn_strides
      ), "The size of feats is not equal to size of fpn_strides"
  
      if self.training:
          return self.forward_train(feats, targets, aux_pred)
      else:
          if targets is not None:
              # only for semi-det
              self.is_teacher = targets.get("is_teacher", False)
              if self.is_teacher:
                  return self.forward_train(
                      feats, targets, aux_pred=None
                  )
              else:
                  return self.forward_eval(feats)
  
          return self.forward_eval(feats)
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from ppdet.core.workspace import register
  from paddle import ParamAttr
  from paddle.nn.initializer import KaimingNormal
  from paddle.nn.initializer import Normal, Constant
  from ..bbox_utils import batch_distance2bbox
  from ..losses import GIoULoss
  from ..initializer import bias_init_with_prob, constant_, normal_
  from ..assigners.utils import generate_anchors_for_grid_cell
  from ppdet.modeling.backbones.cspresnet import ConvBNLayer, RepVggBlock
  from ppdet.modeling.ops import get_static_shape, get_act_fn
  from ppdet.modeling.layers import MultiClassNMS
label_desc: Use image node_id 7 for calling the PPYOLOEHead obj's underlying member method code with example usage: obj.forward(feats, targets, aux_pred) and returns: self, self, self, self