code: def forward(self, x):
      if self.conv_down is not None:
          x = self.conv_down(x)
      y1 = self.conv1(x)
      y2 = self.blocks(self.conv2(x))
      y = paddle.concat([y1, y2], axis=1)
      if self.attn is not None:
          y = self.attn(y)
      y = self.conv3(y)
      return y
  
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 paddle import ParamAttr
  from paddle.regularizer import L2Decay
  from paddle.nn.initializer import Constant
  from ppdet.modeling.ops import get_act_fn
  from ppdet.core.workspace import register, serializable
  from ..shape_spec import ShapeSpec
label_desc: Use image node_id 2 for calling the CSPResStage obj's underlying member method code with example usage: obj.forward(x) and returns: y