code: def doUnitConversions(self):
          
           # Image information
          _handle = fileutil.openImage(self._filename, mode='readonly', memmap=False)
  
          for chip in self.returnAllChips(extname=self.scienceExt):
              conversionFactor = 1.0
              if '/S' in chip._bunit:
                  conversionFactor = chip._exptime
              else:
                  print("Input %s[%s,%d] already in units of ELECTRONS"
                        %(self._filename,self.scienceExt,chip._chip))
  
              chip._effGain = 1.0# chip._gain #1.
              chip._conversionFactor = conversionFactor #1.
  
          _handle.close()
          self._effGain= 1.0
docs: WF3 IR data come out in electrons, and I imagine  the
           photometry keywords will be calculated as such, so no image
           manipulation needs be done between native and electrons