code: def test_io_vtp():
      io_tractogram("vtp")
  
imports: import os
  from tempfile import TemporaryDirectory
  from urllib.error import URLError, HTTPError
  from dipy.data import get_fnames
  from dipy.io.streamline import load_tractogram, save_tractogram, load_trk, save_trk
  from dipy.io.stateful_tractogram import Space, StatefulTractogram
  from dipy.io.utils import create_nifti_header
  from dipy.io.vtk import save_vtk_streamlines, load_vtk_streamlines
  from dipy.tracking.streamline import Streamlines
  import numpy
  import numpy.testing
  import pytest
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 8 for calling a global function with example usage: test_io_vtp() without return types