Functor Contraction.Make

module Make: 
functor (G : G) -> sig .. end
G : G

val contract : (Contraction.G.E.t -> bool) -> Contraction.G.t -> Contraction.G.t
contract p g will perform edge contraction on the graph g. The edges for which the property p holds/is true will get contracted: The resulting graph will not have these edges; the start- and end-node of these edges will get united.