docs: def from_binary_string(cls, stream):
          """
          Read feedback information from the stream and unpack it.
          :param stream: A stream of feedback data from APN. Can contain multiple
          feedback tuples, as defined in the feedback service protocol.
          :return A list containing all unpacked feedbacks.
          """
          offset = 0
          length = len(stream)
          feedbacks = []
  
          while offset < length:
              timestamp, token_length = struct.unpack(cls.FORMAT_PREFIX,
                                                      stream[offset:offset+6])
              when = datetime.fromtimestamp(timestamp)
              offset += 6
              token = struct.unpack('>{0}s'.format(token_length),
                                    stream[offset:offset+token_length])[0]
              token = binascii.hexlify(token)
              offset += token_length
              feedbacks.append(cls(when, token))
  
          return feedbacks