code: def decode(self, value, value_type):
          
          if value_type == 'i':
              return int(value)
  
          if value_type == 'z':
              value = zlib.decompress(value)
              value_type = 'p'
  
          if value_type == 'p':
              return pickle.loads(force_bytes(value))
  
          raise ValueError(
              "Unknown value_type '{}' read from the cache table."
              .format(value_type),
          )
docs: Take a value blob and its value_type one-char code and convert it back
          to a python object