<mo> Stretching Tests

f (\frac{\frac{a}{b} + c}{\frac{c}{d} + e}) + g [x_{\frac{c}{d} + e}^{\frac{a}{b} + c}] + \int_{a}^{b} \sum_{i = 0}^{n} i

Implied mrow with operator stretching:

\sqrt{f (\frac{1}{y})}