Alternately present two csv files

If this template helps then use it. If not then just delete and start from scratch.

OS ( Win10):
PsychoPy version (2.4):
**Standard Standalone? (y)
What are you trying to achieve?:
I did a fraction comparison test, which consists of two stages (each stage has a csv file). What I’m looking for is to present block A and then block B to half the users and to the rest change the order by block B and then block A. I work in builder

thank you very much