code: def read_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_SINGLE)
docs: Read the difference between two ADC channels and return the ADC value
          as a signed integer result.  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