1. 第二种方式可以节省寻找result的append属性的时间, 但会降低代码可读性和可维护性
# The way we're used to seeing it:
result.append("hello") # But this works the same:
append_result = result.append
append_result("hello")
2. 将Python内置的方法在函数内重命名：寻找局部变量快于寻找全局变量和内置变量
# -*- coding:utf-8 -*-
# local to a function, global to a module, or built-in to Python
to_str = str