class_docstr: FoveaBox: Beyond Anchor-based Object Detector
  https://arxiv.org/abs/1904.03797
code: def _init_layers(self):
      # box branch
      super()._init_reg_convs()
      self.conv_reg = nn.Conv2d(self.feat_channels, 4, 3, padding=1)
  
      # cls branch
      if not self.with_deform:
          super()._init_cls_convs()
          self.conv_cls = nn.Conv2d(
              self.feat_channels, self.cls_out_channels, 3, padding=1
          )
      else:
          self.cls_convs = nn.ModuleList()
          self.cls_convs.append(
              ConvModule(
                  self.feat_channels,
                  (self.feat_channels * 4),
                  3,
                  stride=1,
                  padding=1,
                  conv_cfg=self.conv_cfg,
                  norm_cfg=self.norm_cfg,
                  bias=self.norm_cfg is None,
              )
          )
          self.cls_convs.append(
              ConvModule(
                  (self.feat_channels * 4),
                  (self.feat_channels * 4),
                  1,
                  stride=1,
                  padding=0,
                  conv_cfg=self.conv_cfg,
                  norm_cfg=self.norm_cfg,
                  bias=self.norm_cfg is None,
              )
          )
          self.feature_adaption = FeatureAlign(
              self.feat_channels,
              self.feat_channels,
              kernel_size=3,
              deform_groups=self.deform_groups,
          )
          self.conv_cls = nn.Conv2d(
              int(self.feat_channels * 4),
              self.cls_out_channels,
              3,
              padding=1,
          )
  
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 2 for calling the FoveaHead obj's underlying member method code with example usage: obj._init_layers() without return types