class_docstr: CSP (Cross Stage Partial) layer with 3 convs, named C3 in YOLOv5
code: def forward(self, x):
      x_1 = self.conv1(x)
      x_1 = self.bottlenecks(x_1)
      x_2 = self.conv2(x)
      x = paddle.concat([x_1, x_2], axis=1)
      x = self.conv3(x)
      return x
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle import ParamAttr
  from paddle.regularizer import L2Decay
  from ppdet.core.workspace import register, serializable
  from ppdet.modeling.initializer import conv_init_
  from ..shape_spec import ShapeSpec
label_desc: Use image node_id 2 for calling the CSPLayer obj's underlying member method code with example usage: obj.forward(x) and returns: x