docs: def check_arguments(cls, conf):
          """
          Sanity checks for options needed for configfile mode.
  
          """
          try:
              # Check we have access to the config file
              f = open(conf['file'], "r")
              f.close()
          except IOError as e:
              raise ArgsError("Cannot open config file '%s': %s" %
                              (conf['file'], e))