Give an example of a function f : [ a , b ] → R {\displaystyle {}f\colon [a,b]\rightarrow \mathbb {R} } which assumes only finitely many values, but is not a staircase function.
![{\displaystyle {}f\colon [a,b]\rightarrow \mathbb {R} }](https://wikimedia.org/api/rest_v1/media/math/render/svg/55b2774f3530b8b9e513afa18a7fe6273a6e71f1)