code: def boolean_string(string):
      low_string = string.lower()
      if low_string not in {"false", "true"}:
          invalidInputError(False, "Not a valid boolean string")
      return low_string == "true"
  
imports: import time
  import argparse
  import tensorflow
  import os
  import sys
  import math
  import collections
  from tensorflow.python.client import timeline
  import json
  from tensorflow.python.ops import partitioned_variables
  import ray
  from bigdl.dllib.utils.log4Error import *
  from bigdl.orca import init_orca_context, stop_orca_context, OrcaContext
  from bigdl.orca.data.utils import process_spark_xshards
  from bigdl.orca.learn.utils import maybe_dataframe_to_xshards
  from bigdl.friesian.feature import FeatureTable
label_desc: Use image node_id 5 for calling a global function with example usage: boolean_string(string) and returns: unknown