code: def test_is_training(self):
      assert DatatypeHelper.is_training("train") is True
      assert DatatypeHelper.is_training("train:evalmode") is False
      assert DatatypeHelper.is_training("train:ordered") is True
      assert DatatypeHelper.is_training("train:stream") is True
  
      assert DatatypeHelper.is_training("valid") is False
      assert DatatypeHelper.is_training("valid:stream") is False
  
      assert DatatypeHelper.is_training("test") is False
      assert DatatypeHelper.is_training("test:stream") is False
  
imports: from parlai.core.opt import Opt
  from parlai.utils.misc import Timer, round_sigfigs, set_namedtuple_defaults, nice_report
  import parlai.utils.strings
  from copy import deepcopy
  import random
  import time
  import unittest
  from parlai.utils.data import DatatypeHelper
  from parlai.utils.curated_response import generate_init_prompot, generate_safe_response
label_desc: Use image node_id 4 for calling the TestDatatypeHelper obj's underlying member method code with example usage: obj.test_is_training() without return types