class_docstr: FoveaBox: Beyond Anchor-based Object Detector
  https://arxiv.org/abs/1904.03797
code: def forward_single(self, x):
      cls_feat = x
      reg_feat = x
      for reg_layer in self.reg_convs:
          reg_feat = reg_layer(reg_feat)
      bbox_pred = self.conv_reg(reg_feat)
      if self.with_deform:
          cls_feat = self.feature_adaption(cls_feat, bbox_pred.exp())
      for cls_layer in self.cls_convs:
          cls_feat = cls_layer(cls_feat)
      cls_score = self.conv_cls(cls_feat)
      return cls_score, bbox_pred
  
imports: import torch
  import torch.nn
  from mmcv.cnn import ConvModule, normal_init
  from mmcv.ops import DeformConv2d
  from mmdet.core import multi_apply, multiclass_nms
  from ..builder import HEADS
  from .anchor_free_head import AnchorFreeHead
label_desc: Use image node_id 4 for calling the FoveaHead obj's underlying member method code with example usage: obj.forward_single(x) and returns: cls_score,  bbox_pred