code: def get_input_spec(model_name, shape, trimap):
      """
      Get the input spec accoring the model_name.
  
      Args:
          model_name (str): The model name
          shape (str): The shape of input image
          trimap (str): Whether a trimap is required
  
      """
      input_spec = [
          {"img": paddle.static.InputSpec(shape=shape, name="img")}
      ]
      if trimap:
          shape[1] = 1
          input_spec[0]["trimap"] = paddle.static.InputSpec(
              shape=shape, name="trimap"
          )
  
      if model_name == "RVM":
          input_spec.append(
              paddle.static.InputSpec(
                  shape=[None, 16, None, None], name="r1"
              )
          )
          input_spec.append(
              paddle.static.InputSpec(
                  shape=[None, 20, None, None], name="r2"
              )
          )
          input_spec.append(
              paddle.static.InputSpec(
                  shape=[None, 40, None, None], name="r3"
              )
          )
          input_spec.append(
              paddle.static.InputSpec(
                  shape=[None, 64, None, None], name="r4"
              )
          )
          input_spec.append(
              paddle.static.InputSpec(
                  shape=[1], name="downsample_ratio"
              )
          )
      return input_spec
  
label_desc: Use image node_id 1 for calling a global function with example usage: get_input_spec(model_name, shape, trimap) and returns: input_spec