code: def test_list_to_csr_all_empty(self):
      label_list = [[], [], [], [], [], []]
      result = list_to_csr(label_list, (6, 4), dtype=np.float64)
  
      self.assertTrue(isinstance(result, csr_matrix))
      self.assertEqual(np.float64, result.dtype)
      self.assertEqual(np.float64, result.data.dtype)
      self.assertEqual(np.int32, result.indices.dtype)
      self.assertEqual(np.int32, result.indices.dtype)
  
imports: import unittest
  import numpy
  from numpy.testing import assert_array_equal
  from scipy.sparse import csr_matrix
  from small_text.base import LABEL_IGNORED, LABEL_UNLABELED
  from small_text.utils.labels import concatenate, csr_to_list, get_flattened_unique_labels, get_ignored_labels_mask, get_num_labels, list_to_csr, remove_by_index
  from tests.utils.testing import assert_csr_matrix_equal
  from tests.utils.datasets import random_sklearn_dataset
label_desc: Use image node_id 13 for calling the LabelUtilsTest obj's underlying member method code with example usage: obj.test_list_to_csr_all_empty() without return types