End-to-end encryption and privacy controls.
Message and call for free* around the world.
Group conversations made simple.
Say it with stickers, voice, GIFs and more.
Reach your customers from anywhere.
设计模式——行为型模式(责任链,命令,解释器,迭代器,中介者,备忘录,观察者,状态,空对象,策略,模板,访问者) https://codingnote.cc/p/17000/