code: def prepare_input(self, image):
      prev_mask = None
      if self.with_prev_mask:
          prev_mask = paddle.slice(
              image,
              axes=[
                  1,
              ],
              starts=[
                  1,
              ],
              ends=[
                  1000,
              ],
          )
          image = paddle.slice(
              image,
              axes=[
                  1,
              ],
              starts=[
                  0,
              ],
              ends=[
                  1,
              ],
          )
          # prev_mask = image[:, 1:, :, :, :]
          # image = image[:, :1, :, :, :]
          if self.binary_prev_mask:
              prev_mask = (prev_mask > 0.5).astype("float32")
  
      image = self.normalization(image)  # why?
      return image, prev_mask
  
imports: import os
  import sys
  import paddle
  import paddle.nn
  import numpy
  from inference.ops import DistMaps3D, ScaleLayer, BatchImageNormalize3D
  from paddleseg.utils import utils
label_desc: Use image node_id 3 for calling the ISModel3D obj's underlying member method code with example usage: obj.prepare_input(image) and returns: image,  prev_mask