code: def ingest_flash(self):
          
  
          self.flash = extract_flash(self.hdulist[0].header, self.hdulist[1])
  
          # Set post-flash to zeros
          if self.flash is None:
              self.flash = np.zeros_like(self.science)
              return
  
          # Apply the flash subtraction if necessary.
          # Not applied to ERR, to be consistent with ingest_dark()
          if self.flshcorr != 'COMPLETE':
              self.science = self.science - self.flash
docs: Process post-flash.