code: def split_4d_nifti(filename, output_folder):
      img_itk = sitk.ReadImage(filename)
      dim = img_itk.GetDimension()
      file_base = filename.split("/")[-1]
      if dim == 3:
          shutil.copy(
              filename,
              join_paths(
                  output_folder, file_base[:-7] + "_0000.nii.gz"
              ),
          )
          return
      elif dim != 4:
          raise RuntimeError(
              "Unexpected dimensionality: {} of file {}, cannot split".format(
                  dim, filename
              )
          )
      else:
          split_4d_to_3d_and_save(img_itk, output_folder, file_base)
  
file_path: PaddleSeg/contrib/MedicalSeg/tools/preprocess_utils/convert_to_decathlon.py
imports: import os
  import shutil
  import numpy
  import SimpleITK
  from multiprocessing import Pool
  from .path_utils import join_paths
label_desc: Use image node_id 4 for calling a global function with example usage: split_4d_nifti(filename, output_folder) without return types