code: def _init_thresh(
      self, inner_channels, serial=False, smooth=False, bias=False
  ):
      in_channels = inner_channels
      if serial:
          in_channels += 1
      self.thresh = nn.Sequential(
          nn.Conv2D(
              in_channels,
              inner_channels // 4,
              3,
              padding=1,
              bias_attr=bias,
              weight_attr=ParamAttr(
                  initializer=nn.initializer.KaimingNormal()
              ),
          ),
          nn.BatchNorm2D(
              inner_channels // 4,
              weight_attr=ParamAttr(
                  initializer=nn.initializer.Constant(1)
              ),
              bias_attr=ParamAttr(
                  initializer=nn.initializer.Constant(1e-4)
              ),
          ),
          nn.ReLU(),
          self._init_upsample(
              inner_channels // 4,
              inner_channels // 4,
              smooth=smooth,
              bias=bias,
          ),
          nn.BatchNorm2D(
              inner_channels // 4,
              weight_attr=ParamAttr(
                  initializer=nn.initializer.Constant(1)
              ),
              bias_attr=ParamAttr(
                  initializer=nn.initializer.Constant(1e-4)
              ),
          ),
          nn.ReLU(),
          self._init_upsample(
              inner_channels // 4, 1, smooth=smooth, bias=bias
          ),
          nn.Sigmoid(),
      )
      return self.thresh
  
file_path: PaddleOCR/benchmark/PaddleOCR_DBNet/models/head/DBHead.py
imports: import paddle
  from paddle import nn, ParamAttr
label_desc: Use image node_id 3 for calling the DBHead obj's underlying member method code with example usage: obj._init_thresh(inner_channels, serial, smooth, bias) and returns: self