code: def testMismatchPosLenShapes(self, dtype, unit):
      test_string = {
          "BYTE": [
              [b"ten", b"eleven", b"twelve"],
              [b"thirteen", b"fourteen", b"fifteen"],
              [b"sixteen", b"seventeen", b"eighteen"],
          ],
          "UTF8_CHAR": [
              [
                  x.encode("utf-8")
                  for x in [
                      "\U0001d229\U0001d227n",
                      "\xc6\u053c\u025bv\u025bn",
                      "tw\u0c1dlv\u025b",
                  ]
              ],
              [
                  x.encode("utf-8")
                  for x in [
                      "th\xcdrt\xea\xean",
                      "f\U0001f604urt\xea\xean",
                      "f\xcd\ua09ctee\ua0e4",
                  ]
              ],
              [
                  x.encode("utf-8")
                  for x in [
                      "s\xcdxt\xea\xean",
                      "se\U00010299enteen",
                      "ei\U0001e920h\x86een",
                  ]
              ],
          ],
      }[unit]
      position = np.array([[1, 2, 3]], dtype)
      length = np.array([2, 3, 4], dtype)
      # Should fail: position/length have different rank
      with self.assertRaises(ValueError):
          string_ops.substr(test_string, position, length)
  
      position = np.array([[1, 2, 3], [1, 2, 3], [1, 2, 3]], dtype)
      length = np.array([[2, 3, 4]], dtype)
      # Should fail: position/length have different dimensionality
      with self.assertRaises(ValueError):
          string_ops.substr(test_string, position, length)
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 12 for calling the SubstrOpTest obj's underlying member method code with example usage: obj.testMismatchPosLenShapes(dtype, unit) without return types