How is my C++11 allowing me to use std::unique and std::erase?

I found this nice two-line code for sorting and de-duplicating a vector at StackOverflow. Beats writing an algo from scratch.

sort( vec.begin(), vec.end() );
vec.erase( unique( vec.begin(), vec.end() ), vec.end() );

I used it in my code, and it compiles ... in C++11

How the heck is it compiling if
https://en.cppreference.com/w/cpp/algorithm/unique
and
https://en.cppreference.com/w/cpp/container/vector/erase2
say that unique and erase have only existed since C++17 and C++20 respectively?

Am I misunderstanding that documentation, or might my C++11 have some "we think this will be in the next standard" enhancements in it?

Thanks!