code: def _resolve_input(variable, variable_name, config_key, config):
      
      if variable is None:
          try:
              variable = config.get(PROFILE, config_key)
          except NoOptionError:
              raise ValueError((
                  'no {} found - either provide a command line argument or '
                  'set up a default by running `apparate configure`'
              ).format(variable_name))
      return variable
docs: Resolve input entered as option values with config values
  
      If option values are provided (passed in as `variable`), then they are
       returned unchanged. If `variable` is None, then we first look for a config
       value to use.
      If no config value is found, then raise an error.
  
      Parameters
      ----------
      variable: string or numeric
          value passed in as input by the user
      variable_name: string
          name of the variable, for clarity in the error message
      config_key: string
          key in the config whose value could be used to fill in the variable
      config: ConfigParser
          contains keys/values in .apparatecfg