module Mark:sig..end
Vertices contains integers marks, which can be set or used by some
algorithms (see for instance module Marking below)
typegraph =Sig_pack.S.t
typevertex =Sig_pack.S.V.t
val clear : Sig_pack.S.t -> unitclear g sets all marks to 0 from all the vertives of g.
val get : Sig_pack.S.V.t -> int
val set : Sig_pack.S.V.t -> int -> unit