def read(self):
raise NotImplementedError<EOL>
Reads 20ms worth of audio.

        Subclasses must implement this.

        If the audio is complete, then returning an empty
        :term:`py:bytes-like object` to signal this is the way to do so.

        If :meth:`is_opus` method returns ``True``, then it must return
        20ms worth of Opus encoded audio. Otherwise, it must be 20ms
        worth of 16-bit 48KHz stereo PCM, which is about 3,840 bytes
        per frame (20ms worth of audio).

        Returns
        --------
        :class:`bytes`
            A bytes like object that represents the PCM or Opus data.