code: def set_core_number(num):
      callZooFunc("float", "setCoreNumber", num)
  
imports: import functools
  import glob
  import os
  import subprocess
  import tempfile
  import uuid
  from urllib.parse import urlparse
  import numpy
  from bigdl.dllib.utils.common import Sample, JTensor, JavaCreator, _get_gateway, _py2java, _java2py
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 21 for calling a global function with example usage: set_core_number(num) without return types