code: def updateKeyword(filename, key, value,show=yes):
      
  
      _fname, _extn = parseFilename(filename)
  
      # Open image whether it is FITS or GEIS
      _fimg = openImage(_fname, mode='update')
  
      # Address the correct header
      _hdr = getExtn(_fimg, _extn).header
  
      # Assign a new value or add new keyword here.
      try:
          _hdr[key] = value
      except KeyError:
          if show:
              print('Adding new keyword ', key, '=', value)
          _hdr[key] = value
  
      # Close image
      _fimg.close()
      del _fimg
docs: Add/update keyword to header with given value.