$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
3.49
\begin{equation} \label{diagram:homotopy-pushout-square9} \begin{gathered} \xymatrix@R =50pt@C=50pt{ A \ar [r]^-{f_0} \ar [d] & A_1 \ar [d] \\ A_1 \ar [r] & A_{01}. } \end{gathered} \end{equation}