code: def _get_env(self, config):
          
          for option, value in config.items():
              env_name = 'SCRAPEKIT_%s' % option.upper()
              value = os.environ.get(env_name, value)
              config[option] = value
          return config
docs: 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_``.