identity sign的用法和样例：
例句
用作名词 (n.)
- A member initializer that specifes an object initializer after the equals sign is an initialization of an embedded object.
成员构造者特指某个等号后面的对象构造者，是内嵌对象的初始化。 - Add the value on the right side of the equal sign to the current value that is contained in the variable on the left side of the equal sign.
将等号右侧的值添加到等号左侧的变量中包含的当前值。
