$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
3.48
\begin{equation} \label{diagram:pushout-lemma2} \begin{gathered} \xymatrix@R =50pt@C=50pt{ \operatorname{Fun}(A,X) & \operatorname{Fun}(A_0,X) \ar [l]_{u} \\ \operatorname{Fun}(A_1,X) \ar [u] & \operatorname{Fun}(A_{01},X), \ar [l] \ar [u] } \end{gathered} \end{equation}