Identity function

In mathematics, a function that always returns the same value that was used as its argument

In mathematics, an identity function, also called an identity relation, identity map or identity transformation, is a function that always returns the value that was used as its argument, unchanged. That is, when f is the identity function, the equality f(x) = x is true for all values of x to which f can be applied.

This keyword could refer to multiple things. Here are some suggestions: