$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
11.2
\begin{equation} \label{diagram:homotopy-pushout-square-A} \begin{gathered} \xymatrix@R =50pt@C=50pt{ A \ar [r] \ar [d] & B \ar [d] \\ C \ar [r] & D} \end{gathered}\end{equation}