pub fn new() -> Self {
        let graph: Graph<Resource, Relation> = Graph::new();
        let id_map: HashMap<String, NodeIndex<u32>> = HashMap::new();

        Dag { graph, id_map }
    }
/// Create a Dag with "root" node
Create a Dag with "root" node
Create a Dag with " root " node
pub fn new() -> Self {
        let graph: Graph<Resource, Relation> = Graph::new();
        let id_map: HashMap<String, NodeIndex<u32>> = HashMap::new();
        Dag { graph, id_map }
    }
pub fn new ( ) -> Self { let graph : Graph < Resource , Relation > = Graph :: new ( ) ; let id_map : HashMap < String , NodeIndex < u32 > > = HashMap :: new ( ) ; Dag { graph , id_map } }
Create a Dag with "root" node
Create a Dag with " root " node