list.sort，
sorted接受可选
key参数。
key函数用于生成比较密钥。
>>> sorted(lst, key=lambda x: x[1], reverse=True)[['I', 219], ['A', 22], ['P', 14], ['V', 13], ['G', 10], ...]>>> sorted(lst, key=lambda x: -x[1])[['I', 219], ['A', 22], ['P', 14], ['V', 13], ['G', 10], ...]>>> import operator>>> sorted(lst, key=operator.itemgetter(1), reverse=True)[['I', 219], ['A', 22], ['P', 14], ['V', 13], ['G', 10], ...]
