You are given a DAG $($Directed Acyclic Graph$)$ with a unique source and

a unique sink. Does the DAG have a unique topological ordering? $($recall

a node is a $$source$$ node if it only has outgoing edges, and a node is a

$$sink$$ node if it only has incoming edges. Also, recall that $$topological

ordering$$ is a linear ordering of the graph such that every edge goes $$from$-$

left$-$to$-$right$,$ i$.$e$.,$ all edges are forward edges like we saw in ex$\mathrm{.}4$ and ex$\mathrm{.}6$

of the previous HW$5).$