code: def test_pad_sequences_str(self):
      a = [["1"], ["1", "2"], ["1", "2", "3"]]
  
      # test padding
      b = sequence_utils.pad_sequences(
          a, maxlen=3, padding="pre", value="pad", dtype=object
      )
      self.assertAllEqual(
          b, [["pad", "pad", "1"], ["pad", "1", "2"], ["1", "2", "3"]]
      )
      b = sequence_utils.pad_sequences(
          a, maxlen=3, padding="post", value="pad", dtype="<U3"
      )
      self.assertAllEqual(
          b, [["1", "pad", "pad"], ["1", "2", "pad"], ["1", "2", "3"]]
      )
  
      # test truncating
      b = sequence_utils.pad_sequences(
          a, maxlen=2, truncating="pre", value="pad", dtype=object
      )
      self.assertAllEqual(b, [["pad", "1"], ["1", "2"], ["2", "3"]])
      b = sequence_utils.pad_sequences(
          a, maxlen=2, truncating="post", value="pad", dtype="<U3"
      )
      self.assertAllEqual(b, [["pad", "1"], ["1", "2"], ["1", "2"]])
  
      with self.assertRaisesRegex(
          ValueError, "`dtype` int32 is not compatible with "
      ):
          sequence_utils.pad_sequences(
              a, maxlen=2, truncating="post", value="pad"
          )
  
imports: from keras import testing
  from keras.utils import sequence_utils
label_desc: Use image node_id 2 for calling the PadSequencesTest obj's underlying member method code with example usage: obj.test_pad_sequences_str() without return types