Undos the last command that modified any objects, you can undo the last 5 commands.
Undo last modify object command.
This function does not return any data.
If you add some objects manually or type in commands in the prompt like this line by line
then type undo 5 times or more, it will only delete the last 5 objects.The first added plane wave source is kept.
If type redo 5 times or more, it will only recover the last 5 objects.