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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _read_buffer(self, data_in):
 """Process the socket buffer, and direct the data to the appropriate channel. :rtype: bytes """

        while data_in:
            data_in, channel_id, frame_in = self._handle_amqp_frame(data_in)

            if frame_in is None:
                break

            self.heartbeat.register_read()
            if channel_id == 0:
                self._channel0.on_frame(frame_in)
            elif channel_id in self._channels:
                self._channels[channel_id].on_frame(frame_in)

        return data_in