code: def stsci(hdulist):
      
  
      instrument = hdulist[0].header.get('INSTRUME', '')
  
      # Update extension header keywords
      if instrument in ("WFPC2", "FOC"):
          rootname = hdulist[0].header.get('ROOTNAME', '')
          filetype = hdulist[0].header.get('FILETYPE', '')
          for i in range(1, len(hdulist)):
              # Add name and extver attributes to match PyFITS data structure
              hdulist[i].name = filetype
              hdulist[i]._extver = i
              # Add extension keywords for this chip to extension
              hdulist[i].header['EXPNAME'] = (rootname, "9 character exposure identifier")
              hdulist[i].header['EXTVER']= (i, "extension version number")
              hdulist[i].header['EXTNAME'] = (filetype, "extension name")
              hdulist[i].header['INHERIT'] = (True, "inherit the primary header")
              hdulist[i].header['ROOTNAME'] = (rootname, "rootname of the observation set")
docs: For STScI GEIS files, need to do extra steps.