  For a set-endofunctor $F$, a graph is triple $(V,E,g)$ with a structure map
$g:E\rightarrow F V$. This model is a generalized coalgebra over the category
of sets. In this note, we model graphs as coalgebras over $Set\times Set$ and
use the theory of coalgebras over arbitrary categories to conclude properties
of the category of graphs.
