How to allow a continuous/sustained key response?

Hi!

I am looking for a way to allow participants sustained/continuous response on a trial. For instance, if they are seeing top-view percept of necker cube, they keep a key pressed. When they switch and see the bottom-view, they keep another key pressed. I was wondering if PsyToolkit allows such sustained responses. I looked up the documentation/forum but couldn't find anything. 

Revati