Gets an item based on the path.

def get(self, callback):
        '''
        Gets an item based on the path.
        '''
        derived_path = self.context.request.url
        logger.debug('[{log_prefix}]: get.derived_path: {path}'.format(
            log_prefix=LOG_PREFIX, path=derived_path))
        callback(self.storage.get(self.result_key_for(derived_path)))