code: def read_adc(self, channel, gain=1, data_rate=None):
          
          assert 0 <= channel <= 3, 'Channel must be a value within 0-3!'
          # Perform a single shot read and set the mux value to the channel plus
          # the highest bit (bit 3) set.
          return self._read(channel + 0x04, gain, data_rate, ADS1x15_CONFIG_MODE_SINGLE)
docs: Read a single ADC channel and return the ADC value as a signed integer
          result.  Channel must be a value within 0-3.