code: def test_single_padding_string(self):
      data = [[b"a"], [b"b", b"c", b"d"], [b"e", b"f"]]
      data_tensor = ragged_factory_ops.constant(data)
      ngram_op = ragged_string_ops.ngrams(
          data_tensor,
          ngram_width=5,
          separator=b"|",
          pad_values=b"[PAD]",
          padding_width=1,
      )
      result = self.evaluate(ngram_op)
      expected_ngrams = [[], [b"[PAD]|b|c|d|[PAD]"], []]
      self.assertAllEqual(expected_ngrams, result)
  
imports: from absl.testing import parameterized
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops.ragged import ragged_factory_ops
  from tensorflow.python.ops.ragged import ragged_string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 11 for calling the StringNgramsTest obj's underlying member method code with example usage: obj.test_single_padding_string() without return types