code: def forward(self, inputs):
      if self.reture_input:
          return inputs
      output1, output2 = None, None
      if "fpn" in self.neck_type:
          backout_4, backout_1 = inputs
          output1, output2 = self.fpn([backout_4, backout_1])
      if self.neck_type == "only_fpn":
          return [output1, output2]
      if self.neck_type == "only_ssh":
          output1, output2 = inputs
      feature1 = self.ssh1(output1)
      feature2 = self.ssh2(output2)
      return [feature1, feature2]
  
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 BlazeNeck obj's underlying member method code with example usage: obj.forward(inputs) and returns: list, inputs, list