Function create_index 

fn create_index<N: Idx + Ord>(
    num_nodes: usize,
    sorted_edge_sources: &mut dyn Iterator<Item = N>,
    associated_edge_targets: &mut dyn Iterator<Item = N>,
    edge_targets: &mut Vec<N>,
    node_starts: &mut IndexVec<N, usize>,
)

Creates/initializes the index for the VecGraph. A helper for VecGraph::new.

• num_nodes is the target number of nodes in the graph
• sorted_edge_sources are the edge sources, sorted
• associated_edge_targets are the edge targets in the same order as sources
• edge_targets is the vec of targets to be extended
• node_starts is the index to be filled