class_docstr: TypeSpec for PerWorkerValues.
  
  It only support tracing a function using a PerWorkerValues.
class_docstr_tok: ["TypeSpec","for","PerWorkerValues",".","It","only","support","tracing","a","function","using","a","PerWorkerValues","."]
code: def __init__(self, value_spec, descendant_type):
      assert value_spec
      self._value_spec = value_spec
      self._descendant_type = descendant_type
  
imports: import threading
  from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.data.ops.options import ExternalStatePolicy
  from tensorflow.python.distribute import input_lib
  from tensorflow.python.distribute.coordinator import remote_value
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.eager import function
  from tensorflow.python.framework import composite_tensor
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import type_spec
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gen_dataset_ops
  from tensorflow.python.ops import gen_experimental_dataset_ops
  from tensorflow.python.ops import variable_scope
  from tensorflow.python.util import nest
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 1 to create a new PerWorkerValuesTypeSpec object from inherited base classes: type_spec_lib with example: obj = PerWorkerValuesTypeSpec(value_spec, descendant_type)