code: def check_in_lambda():
      
      if not os.getenv(LAMBDA_TASK_ROOT_KEY):
          return None
  
      try:
          os.mkdir(TOUCH_FILE_DIR)
      except OSError:
          log.debug('directory %s already exists', TOUCH_FILE_DIR)
  
      try:
          f = open(TOUCH_FILE_PATH, 'w+')
          f.close()
          # utime force second parameter in python2.7
          os.utime(TOUCH_FILE_PATH, None)
      except (IOError, OSError):
          log.warning("Unable to write to %s. Failed to signal SDK initialization." % TOUCH_FILE_PATH)
  
      return LambdaContext()
docs: Return None if SDK is not loaded in AWS Lambda worker.
      Otherwise drop a touch file and return a lambda context.