code: def test_writeable_data(self):
      data = DATA["simple_tractogram"]
      for key in ("simple_tck_fname", "simple_tck_big_endian_fname"):
          for lazy_load in [False, True]:
              tck = TckFile.load(DATA[key], lazy_load=lazy_load)
              for actual, expected_tgi in zip(tck.streamlines, data):
                  assert_array_equal(actual, expected_tgi.streamline)
                  # Test we can write to arrays
                  assert actual.flags.writeable
                  actual[0, 0] = 99
  
imports: import os
  import unittest
  from io import BytesIO
  from os.path import join
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from ...testing import data_path, error_warnings
  from ..None import tck
  from ..array_sequence import ArraySequence
  from ..tck import TckFile
  from ..tractogram import Tractogram
  from ..tractogram_file import DataError, HeaderError, HeaderWarning
  from .test_tractogram import assert_tractogram_equal
label_desc: Use image node_id 8 for calling the TestTCK obj's underlying member method code with example usage: obj.test_writeable_data() without return types