Read environment variables based on the settings defined in
        the defaults. These are expected to be upper-case versions of
        the actual setting names, prefixed by ``SCRAPEKIT_``.

def _get_env(self, config):
        """ Read environment variables based on the settings defined in
        the defaults. These are expected to be upper-case versions of
        the actual setting names, prefixed by ``SCRAPEKIT_``. """
        for option, value in config.items():
            env_name = 'SCRAPEKIT_%s' % option.upper()
            value = os.environ.get(env_name, value)
            config[option] = value
        return config