def _request_headers(self):
        """
        Sets the default Request Headers.
        """

        headers = {
            'X-Contentful-User-Agent': self._contentful_user_agent(),
            'Content-Type': 'application/vnd.contentful.delivery.v{0}+json'.format(  # noqa: E501
                self.api_version
            )
        }

        if self.authorization_as_header:
            headers['Authorization'] = 'Bearer {0}'.format(self.access_token)

        headers['Accept-Encoding'] = 'gzip' if self.gzip_encoded else 'identity'

        return headers
Sets the default Request Headers.