Input:
`integrate(integrate(x + y, y))`
Compute:
$$\int \int (x+y)\ dy\ dx$$
Result:
$$\frac{1}{2}\ x^{2}\ y+\frac{1}{2}\ x\ y^{2}$$
LaTeX:
\frac{1}{2}\ x^{2}\ y+\frac{1}{2}\ x\ y^{2}
$$\int \int (x+y)\ dy\ dx == \frac{1}{2}\ x^{2}\ y+\frac{1}{2}\ x\ y^{2}$$