code: def test_concatenate():
      filepath_dix, _, _ = get_fnames("gold_standard_tracks")
      sft = load_tractogram(
          filepath_dix["gs.trk"], filepath_dix["gs.nii"]
      )
      trx = tmm.load(filepath_dix["gs.trx"])
      concat = concatenate_tractogram([sft, trx])
  
      assert len(concat) == 2 * len(trx)
      trx.close()
      concat.close()
  
imports: import trx.trx_file_memmap
  from dipy.data import get_fnames
  from dipy.io.streamline import load_tractogram
  from dipy.utils.tractogram import concatenate_tractogram
label_desc: Use image node_id 1 for calling a global function with example usage: test_concatenate() without return types