code: def forward(self, input):
      output1 = self.conv1_fpn(input[0])
      output2 = self.conv2_fpn(input[1])
      up2 = F.upsample(
          output2, size=paddle.shape(output1)[-2:], mode="nearest"
      )
      output1 = paddle.add(output1, up2)
      output1 = self.conv3_fpn(output1)
      return output1, output2
  
imports: import paddle
  import paddle.nn.functional
  from paddle import ParamAttr
  import paddle.nn
  from paddle.nn.initializer import KaimingNormal
  from ppdet.core.workspace import register, serializable
  from ..shape_spec import ShapeSpec
label_desc: Use image node_id 2 for calling the FPN obj's underlying member method code with example usage: obj.forward(input) and returns: output1,  output2