Return a cache key from a given set of request parameters.

            Default behavior is to return a complete URL for all GET
            requests, and None otherwise.

            Can be overriden if caching of non-get requests is desired.

def key_for_request(self, method, url, **kwargs):
        """ Return a cache key from a given set of request parameters.

            Default behavior is to return a complete URL for all GET
            requests, and None otherwise.

            Can be overriden if caching of non-get requests is desired.
        """
        if method != 'get':
            return None

        return requests.Request(url=url, params=kwargs.get('params', {})).prepare().url