code: def testResultTypeStr(self):
      with DtypeConversionTestEnv("all"):
          res = flexible_dtypes.result_type("foo", "bar")
          self.assertEqual(res[0], dtypes.string)
          with self.assertRaisesRegex(
              NotImplementedError,
              "Implicit Conversion between <dtype: 'string'> and <dtype: 'int32'>"
              " is not allowed. Please convert the input manually if you need to.",
          ):
              flexible_dtypes.result_type("foo", 1)
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import extension_type
  from tensorflow.python.framework import flexible_dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import weak_tensor
  from tensorflow.python.ops import variables
  from tensorflow.python.ops import weak_tensor_test_util
  from tensorflow.python.platform import test
label_desc: Use image node_id 17 for calling the DtypesUtilTest obj's underlying member method code with example usage: obj.testResultTypeStr() without return types