\end{section}
\begin{section}{Arrow}
- The identity operator on $V$ is $\identity{V}$. The composition of
- $f$ and $g$ is $\compose{f}{g}$. The inverse of $f$ is
+ The constant function that always returns $a$ is $\const{a}$. The
+ identity operator on $V$ is $\identity{V}$. The composition of $f$
+ and $g$ is $\compose{f}{g}$. The inverse of $f$ is
$\inverse{f}$. If $f$ is a function and $A$ is a subset of its
domain, then the preimage under $f$ of $A$ is $\preimage{f}{A}$.
\end{section}