实现事件溯源（Event Sourcing）

solve()

ORD001: status=shipped, amount=598.0
ORD002: status=cancelled, amount=0
ORD003: status=completed, amount=264.0
ORD016: status=paid, amount=97.77
ORD017: status=pending, amount=0
ORD018: status=paid, amount=764.41
ORD019: status=paid, amount=496.79
ORD020: status=pending, amount=0
ORD021: status=shipped, amount=0
ORD022: status=pending, amount=0
ORD023: status=paid, amount=585.77
ORD024: status=shipped, amount=0
ORD025: status=shipped, amount=0
ORD026: status=paid, amount=599.75
ORD027: status=shipped, amount=0
ORD028: status=pending, amount=0
ORD029: status=shipped, amount=0
ORD030: status=pending, amount=0
ORD031: status=pending, amount=0
ORD032: status=paid, amount=461.85
ORD033: status=paid, amount=463.71
ORD034: status=shipped, amount=0
ORD035: status=paid, amount=463.8
ORD036: status=paid, amount=859.13
ORD037: status=pending, amount=0
ORD038: status=paid, amount=369.58
ORD039: status=paid, amount=513.17
ORD040: status=paid, amount=315.68