example.py

def execute(self, command_name, *args):
        """Execute a pre defined command and log in history"""
        if command_name in self._commands.keys():
            self._history_position += 1
            self._commands[command_name].execute(args)
            if len(self._history) == self._history_position:
                # This is a new event in hisory
                self._history.append((time.time(), command_name, args))
            else:
                # This occurs if there was one of more UNDOs and then a new
                # execute command happened. In case of UNDO, the history_position
                # changes, and executing new commands purges any history after
                # the current position"""
                self._history = self._history[:self._history_position+1]
                self._history[self._history_position] = {
                    time.time(): [command_name, args]
                }
        else:
            print(f"Command [{command_name}] not recognised")