code: def _get_cache_key(self):
          keys = list(self.params.keys())
          keys.sort()
          cache_key = str()
          for key in keys:
              if key != "api_sig" and key != "api_key" and key != "sk":
                  cache_key += key + self.params[key]
          return hashlib.sha1(cache_key.encode("utf-8")).hexdigest()