code: def testUnregisteredTypeSpec(self):
      structure = {"x": UnregisteredTypeSpec()}
      self.assertFalse(nested_structure_coder.can_encode(structure))
      with self.assertRaises(nested_structure_coder.NotEncodableError):
          nested_structure_coder.encode_structure(structure)
  
imports: import collections
  import typing
  import warnings
  import numpy
  from google.protobuf import text_format
  from tensorflow.core.protobuf import struct_pb2
  from tensorflow.python.data.ops import dataset_ops
  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 sparse_tensor
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.framework import test_util
  from tensorflow.python.framework import type_spec
  from tensorflow.python.framework import type_spec_registry
  from tensorflow.python.ops.ragged import ragged_tensor
  from tensorflow.python.platform import test
  from tensorflow.python.saved_model import nested_structure_coder
  from tensorflow.python.types import internal
label_desc: Use image node_id 24 for calling the NestedStructureCoderTest obj's underlying member method code with example usage: obj.testUnregisteredTypeSpec() without return types