Add the ability to setup and share recurring events. For example, I plan to go to NY nightowls for the next couple of weeks and it would be good to let other people know that it's happening every Tuesday night from 9pm-3am.
Bonus points if you can figure out:
1) Plans with changing venues but constant recurring schedules
2) How to let a user opt-out of just one or a couple of the recurring events while counting themselves in to the entire series
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