How to do nested loop?

I am a beginner in psychpy. please suggest to me how to do a nested loop and make randomization between conditions. I can’s get any clue at all. In my experiment among three condition any of them will come first. Withing each condition there will be 4 trials with need to be the same in sequence. . In this study phase in my picture there are three condition I have to show them apart with random sequence.
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Hi @Mollika_Roy, take a look at the documentation for blocks and counterbalancing. This should have all the information you require, but please ask more questions if you get stuck.