It's just a regex. When the model outputs "[calculate]12+34=[/calculate]" you append the result "46" and continue with the model. In some papers they even use

It's just a regex. When the model outputs "[calculate]12+34=[/calculate]" you append the result "46" and continue with the model. In some papers they even use named symbols. So you could have "[code]width=10; height=20[/code]. What is the area? ... The area is [code]width * height[/code].