code: def smart_constant_value(pred):
      """Return the bool value for `pred`, or None if `pred` had a dynamic value.
  
      Args:
        pred: A scalar, either a Python bool or tensor.
  
      Returns:
        True or False if `pred` has a constant boolean value, None otherwise.
  
      Raises:
        TypeError: If `pred` is not a Tensor or bool.
      """
      if isinstance(pred, tensor.Tensor):
          pred_value = tensor_util.constant_value(pred)
          # TODO(skyewm): consider folding this into tensor_util.constant_value.
          # pylint: disable=protected-access
          if pred_value is None:
              pred_value = tensor_util.try_evaluate_constant(pred)
          # pylint: enable=protected-access
      elif pred in {0, 1}:  # Accept 1/0 as valid boolean values
          pred_value = bool(pred)
      elif isinstance(pred, bool):
          pred_value = pred
      else:
          raise TypeError(
              "Argument `pred` must be a Tensor, or a Python bool, or 1 "
              f"or 0. Received: pred={pred} of type "
              f"{type(pred).__name__}"
          )
  
      return pred_value
  
imports: from tensorflow.python.framework import tensor
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.ops import cond
  from tensorflow.python.ops import control_flow_case
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 2 for calling a global function with example usage: smart_constant_value(pred) and returns: pred_value