$$\begin{array}{ccc}\hfill 1\hfill & \hfill \to \hfill & \hfill 2\hfill \\ \hfill \downarrow \hfill & \hfill x+\frac{2}{y^3}\hfill & \hfill \downarrow \hfill \\ \hfill 3\hfill & \hfill \to \hfill & \hfill 4\hfill \end{array}$$