code: def getReadNoise(self):
          
          if self.proc_unit == 'native':
              return self._rdnoise / self._gain()
          return self._rdnoise
docs: Method for returning the readnoise of a detector (in DN).
  
          :units: DN
  
          This should work on a chip, since different chips to be consistant with other
          detector classes where different chips have different gains.