Macro graph 

macro_rules! graph {
    (
        with_node: $node:expr,
        with_edges: $type:tt,
        nodes: [$($ident:expr),*],
        connections: [ $($from:expr => {$(($cost:expr) $to:expr),+}),* ]
    ) => { ... };
    (
        nodes: [$($ident:expr => $node:expr),*],
        connections: [ $($from:expr => {$(($type:tt, $cost:expr) {$($to:expr),+}),+}),* ]
    ) => { ... };
}