pub trait GraphEdgeMutIndexable<E>: GraphBase + GraphEdgeIndexable<E> {
// Required method
fn edge_mut(&mut self, id: Self::EdgeID) -> &mut E;
}
pub trait GraphEdgeMutIndexable<E>: GraphBase + GraphEdgeIndexable<E> {
// Required method
fn edge_mut(&mut self, id: Self::EdgeID) -> &mut E;
}