 }
 
 struct Edge {
-    enum Operator: String {
-        case undirected = "--"
-        case directed = "->"
-    }
-
     var from: Node
     var to: Node
 }


extension Edge: Statement {
    func serialize(with context: Graph) -> String {
        return "\(from.identifier) \(context.type.op.rawValue) \(to.identifier)"
    }
}


        case undirected = "graph"
        case directed = "digraph"

        var edgeOperator: String {
            switch self {
            case .undirected: return "--"
            case .directed: return "->"
            }
        }
    }
