$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
5.12
\begin{equation} \begin{gathered}\label{equation:defining-contravariant-transport} \xymatrix@R =50pt@C=50pt{ X \ar [d]^{u} \ar [r]^-{ \widetilde{f}_{X} } & f_{!}(X) \ar [d]^{ f_{!}(u) } \\ Y \ar [r]^-{ \widetilde{f}_{Y} } & f_{!}(Y) } \end{gathered} \end{equation}