It would be nice if there was a function to create an edge-weighted digraph from a given digraph by assigning each edge a weight of 1, e.g. UnitEdgeWeightedDigraph(D). Currently if you want to do this you need to call something like

gap> EdgeWeightedDigraph(D, List(DigraphVertices(D), x -> ListWithIdenticalEntries(OutDegreeOfVertex(D, x), 1)));

which is a bit cumbersome, especially when using the gap REPL. The reason for having such a function is that it is sometimes useful to call weighted digraph functions such as DigraphMaximumFlow on unweighted digraphs by assuming each edge has unit weight.

An alternative would be to modify the weighted graph functions to also accept unweighted digraphs as input, and automatically add unit weights to them if they are unweighted, but this might be a bit harder to maintain.