code: def is_built_in_function(payload):
      # The payload may be a pickled bytes or the class name of the built-in functions.
      # If it represents a built-in function, it will start with 0x00.
      # If it is a pickled bytes, it will start with 0x80.
      return payload[0] == 0
  
imports: import datetime
  import threading
  import time
  from collections.abc import Generator
  from functools import partial
  from typing import Any, Tuple, Dict, List
  from pyflink.common import Row
  from pyflink.fn_execution import pickle
  from pyflink.serializers import PickleSerializer
  from pyflink.table import functions
  from pyflink.table.udf import DelegationTableFunction, DelegatingScalarFunction, ImperativeAggregateFunction, PandasAggregateFunctionWrapper
label_desc: Use image node_id 9 for calling a global function with example usage: is_built_in_function(payload) and returns: unknown