code: def test_slice_start_only(self):
      regions_start = [i * 1000 for i in range(n_slices)]
      slice_source_at_stamps(
          self.source_file, regions_start, output_dir=self.output_dir
      )
  
imports: from numpy.testing import TestCase, assert_equal
  from aubio import slice_source_at_stamps
  from utils import count_files_in_directory, get_default_test_sound
  from utils import count_samples_in_directory, count_samples_in_file
  import tempfile
  import shutil
label_desc: Use image node_id 2 for calling the aubio_slicing_test_case obj's underlying member method code with example usage: obj.test_slice_start_only() without return types