A function \\(f\colon \mathbb{R}\to\mathbb{R}\\) is

1. _order-preserving_ if \\(x\leq y\\) implies \\(f(x)\leq f(y)\\), for all \\(x,y\in\mathbb{R}\\);
2. _metric-preserving_ if \\(|x-y|=|f(x)-f(y)|\\);
3. _addition-preserving_ if \\(f(x+y)=f(x)+f(y)\\).

In each of the three cases above, find an \\(f\\) that is _foo_-preserving and an example of an \\(f\\) that is not _foo_-preserving.