code: def rebind_string(self, keysym, newstring):
          
          if newstring is None:
              try:
                  del self.keysym_translations[keysym]
              except KeyError:
                  pass
          else:
              self.keysym_translations[keysym] = newstring
docs: Change the translation of KEYSYM to NEWSTRING.
          If NEWSTRING is None, remove old translation if any.