val party1 = ...
val party2 = ...
val recip = ...
Init: t1:Transaction if t1.sender=party1 && t1.amount > 500 NXT => | S1
t2:Transaction if t2.sender=party2 && t2.amount > 1500 NXT => | S2
S1:
t2:Transaction if t2.sender=party2 && t1.amount > 500 NXT=> | S3
S2:
t1:Transaction if t1.sender=party1 && t2.amount > 1500 NXT=> | S3
S3: _ => newTransaction(t, recipient=recip, amount=t1.amount+t2.amount) | Finish