code: def check_missing_key(config, key, msg, log=logger):
      """Verify important key is present, otherwise raise exception
  
      :param config: configuration
      :type config: dict
      :param key: key name
      :type key: str
      :param msg: warning message when key is not present
      :type msg: str
      :param log: logger obj to trace where the function is called, default is aup.utils
      :type log: logging.Logger
      """
      if key not in config:
          log.error(msg)
          raise KeyError(msg)
  
imports: from __future__ import print_function
  import sys
  import logging
  import os
  from os import path
  from six.moves import input
  from six.moves.configparser import ConfigParser
  import paramiko
  from paramiko import SFTPClient
  from .aup import BasicConfig, print_result
label_desc: Use image node_id 1 for calling a global function with example usage: check_missing_key(config, key, msg, log) without return types