code: def start_adc_difference(self, differential, gain=1, data_rate=None):
          
          assert 0 <= differential <= 3, 'Differential must be a value within 0-3!'
          # Perform a single shot read using the provided differential value
          # as the mux value (which will enable differential mode).
          return self._read(differential, gain, data_rate, ADS1x15_CONFIG_MODE_CONTINUOUS)
docs: Start continuous ADC conversions between two ADC channels. Differential
          must be one of:
            - 0 = Channel 0 minus channel 1
            - 1 = Channel 0 minus channel 3
            - 2 = Channel 1 minus channel 3
            - 3 = Channel 2 minus channel 3
          Will return an initial conversion result, then call the get_last_result()
          function continuously to read the most recent conversion result.  Call
          stop_adc() to stop conversions.