#2 conflict w/events occurring at same time

[Alan Liu]

Events scheduled for the same time are processed in
FIFO order, however this breaks the ability to hold
consecutive classes because th EndClass event is
scheduled after an UnscheduleClass event, but also
after a ScheduleClass event for the proceeding class.

time (increasing)
| Class scheduled, EndClass event scheduled
| Class occurs and schedules next class
| AttendClass action, "stop attending class" event
scheduled
|
| *at the same time* EndClass event happens, then
next Class event happens, but "stop attending class"
happens and nullifies next class
v