code: def check_toplevel_config(what, who):
      
      config_name = what.config_name
      config = get_global_config()
      if config_name not in config:
          raise ConfigurationError(
              '{0} requires top-level configuration for {1}'
              .format(who, config_name))
      checker = getattr(what, 'check_config', None)
      if checker:
          checker(config[config_name], config_name)
docs: Verify that some dependent configuration is present and correct.
  
      This will generally be called from a
      :meth:`~yakonfig.Configurable.check_config` implementation.
      `what` is a :class:`~yakonfig.Configurable`-like object.  If the
      corresponding configuration isn't present in the global
      configuration, raise a :exc:`yakonfig.ConfigurationError`
      explaining that `who` required it.  Otherwise call that module's
      :meth:`~yakonfig.Configurable.check_config` (if any).
  
      :param yakonfig.Configurable what: top-level module to require
      :param str who: name of the requiring module
      :raise yakonfig.ConfigurationError: if configuration for
        `what` is missing or incorrect