code: def test_is_label_valid(self):
      labels = [[1.0, 0.0, -1.0]]
      labels_validity = [[True, True, False]]
      is_valid = utils.is_label_valid(labels)
      self.assertAllEqual(is_valid, labels_validity)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import tensorflow
  from tensorflow_ranking.python import utils
label_desc: Use image node_id 1 for calling the UtilsTest obj's underlying member method code with example usage: obj.test_is_label_valid() without return types