code: def clear(self):
          ''' Clear the undo list. '''
          self._undos.clear()
          self._redos.clear()
          self._savepoint = None
          self._receiver = self._undof clear(self):
          ''' Clear the undo list. '''
          self._undos.clear()
          self._redos.clear()
          self._savepoint = None
          self._receiver = self._undos
docs: Clear the undo list.