code: def test_input_with_no_values(self):
      data = ragged_factory_ops.constant(
          [[], [], []], dtype=dtypes.string
      )
      ngram_op = ragged_string_ops.ngrams(data, (1, 2))
      result = self.evaluate(ngram_op)
      self.assertAllEqual([0, 0, 0, 0], result.row_splits)
      self.assertAllEqual(
          constant_op.constant([], dtype=dtypes.string), result.values
      )
  
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 22 for calling the StringNgramsTest obj's underlying member method code with example usage: obj.test_input_with_no_values() without return types