code: def isnan(val):
      # NaN is never equal to itself.
      return val != val
  
imports: import copy
  import math
  import operator
  import pickle
  import unittest
  from google.protobuf import unittest_import_pb2
  from google.protobuf import unittest_pb2
  from google.protobuf.internal import api_implementation
  from google.protobuf.internal import test_util
  from google.protobuf import message
label_desc: Use image node_id 1 for calling a global function with example usage: isnan(val) and returns: unknown