Sometimes when dealing with multiple integrals we need to integrate inside a region bounded by graphs of functions. This leads to integrals of the form:
$$I=\int_{a}^b\int_{f(x)}^{g(x)}\xi(x,y)dydx.$$
One concrete example I came accross recently is the following, consider the region $R$ defined by
$$R=\{(x,y)\in \mathbb{R}^2 : 0\leq x\leq \operatorname{arcsinh}(2), 0\leq y\leq \arctan(\sinh(x))\}$$
This region is bounded by the graph $y = 0$ and $y = \arctan(\sinh(x))$.
If I want to integrate one function of two variables in a region like this, how can I proceed? How Mathematica deals with this?