關於key？

1、sorted

print(sorted([-5,3,-4,2,-1],key=abs))   # [-1,2,3,-4,-5]
list2 = ['sunv',(1,2),'a',[1,2,3]]
print(sorted(list2,key=len,reverse=True))   # ## ['sunv', [1, 2, 3], (1, 2), 'a']

2、max/min

print(max(dic,key=lambda k:dic[k]))

print(min([-9,2,23,59],key = abs))  # 輸出絕對值最小的數    # 2

3、函數的關鍵字參數(key=balabala)
4、