Vertices reachable from a vertex
VertexOutComponent[g, {v1, v2, …}]
VertexOutComponent[g, {v1, v2, …}, k]
VertexOutComponent[g, {v1, v2, …}, {k}]
VertexOutComponent[{v -> w, …}, …]
VertexOutComponent[{1 -> 2, 1 -> 5, 2 -> 3, 3 -> 4, 4 -> 5, 6 -> 3, 4 -> 6}, {3}]
→ {3, 4, 5, 6}