类似_xxx和__xxx这样的函数或变量就是非公开的(private),不应该被直接引用,比如_abc,__abc等;
# private私有函数def _private_1(name): return 'Hello,%s'%namedef _private_2(name): return 'Hi,%s'%name# public公开函数def greeting(name): if len(name) > 3: return _private_1(name) else: return _private_2(name)print(greeting('frank'))