code: def testWordCount(self):
      with tf.compat.v1.Graph().as_default():
          string_tensor = tf.constant(
              ["abc", "def", "fghijklm", "z", ""]
          )
          tokenized_tensor = tf.compat.v1.string_split(
              string_tensor, delimiter=""
          )
          output_tensor = mappers.word_count(tokenized_tensor)
          output_3d_tensor = mappers.word_count(
              tf.sparse.expand_dims(
                  tf.sparse.expand_dims(tokenized_tensor, axis=1),
                  axis=1,
              )
          )
          with tf.compat.v1.Session():
              output = output_tensor.eval()
              self.assertEqual(5, len(output))
              self.assertEqual(15, sum(output))
              self.assertAllEqual(output, [3, 3, 8, 1, 0])
              self.assertAllEqual(output, output_3d_tensor.eval())
  
imports: import numpy
  import tensorflow
  from tensorflow_transform import mappers
  from tensorflow_transform import test_case
label_desc: Use image node_id 16 for calling the MappersTest obj's underlying member method code with example usage: obj.testWordCount() without return types