graphable interface

lib/Graphable.ts

@@ -0,0 +1,5 @@
+import { Graph } from './Graph';
+
+export interface Graphable {
+  to_graph(g: Graph): void;
+}

lib/index.ts

@@ -5,3 +5,4 @@ export { Edge } from './Edge';
 export { Color } from './Color';
 export { EdgeStyles, NodeStyles, GraphStyles } from './Styles';
 export { GraphLayouts } from './GraphLayouts';
+export { Graphable } from './Graphable';