# Module type Sig.EDGE

    module type EDGE = sig .. end

Signature for edges.

Edges are `Sig.ORDERED_TYPE`.

    type t

    val compare : t -> t -> int

Edges are directed.

    type vertex

    val src : t -> vertex

Edge origin.

    val dst : t -> vertex

Edge destination.
Edges are labeled.

    type label

    val create : vertex -> label -> vertex -> t

`create v1 l v2` creates an edge from `v1` to `v2` with label `l`

    val label : t -> label

Get the label of an edge.