public static IEnumerable <TEdge> GetInEdges <TVertex, TEdge>(this IBidirectionalGraph <TVertex, TEdge> graph, TVertex vertex)
where TEdge : IEdge <TVertex>
{
var result = new List <TEdge>();
IEnumerable <TEdge> edges;
graph.TryGetInEdges(vertex, out edges);
if (edges != null)
{
result.AddRange(edges);
}
return(result);
}