Math Help - contradict fubin's theorem

can anyone give an example of a function f(x,y) for which fubini's theorem is not valid.

This is taken from Stewart's Calculus book

$\int_0^1 \!\!\! \int_0^1 \dfrac{x-y}{(x+y)^3}\,dx\,dy$ and $\int_0^1 \!\!\! \int_0^1 \dfrac{x-y}{(x+y)^3}\,dy\,dx$.

Saurabmtz, Fubini's theorem requires that the integrand be continous on $a\le x\le b$, $c\le y\le d$ where a, b, c, and d are the limits on the appropriate integrals. This integrand is not continuous at (0, 0).