Accessing table columns

We can access table rows using either the relevant newtype or i32 (which is identical to the tskit-c typedef tsk_id_t). The following snippet adds and edge and then validates the data for that row of the table:

    if let Ok(edge_id) = tables.add_edge(left, right, parent, child) {
        // Take a reference to an edge table (& tskit::EdgeTable)
        let edges = tables.edges();
        if let Some(p) = edges.parent(edge_id) {
            assert_eq!(p, parent);
        if let Some(c) = edges.child(edge_id) {
            assert_eq!(c, child);
        if let Some(l) = edges.left(edge_id) {
            assert_eq!(l, left);
        if let Some(r) = edges.right(edge_id) {
            assert_eq!(r, right);
    } else {
        panic!("that should have worked...");

The return type of the getters is the Option enum. The None variant is returned when row indexes are out of range: