identity functor

例句：

1. 1. The two people share the same identity as siblings.
   这两个人有着兄弟姐妹相同的身份。
2. 2. Identity is a complex concept that has been studied for centuries.
   身份是一个复杂的概念，已经研究了几个世纪了。
3. 3.The identity of the suspect was never established.
   嫌疑人的身份从未得到确认。