Function get_start_node

src/navigate.rs:380–392

(mathml: Element<'m>, nav_state: &RefMut<NavigationState>)

    });

    fn get_start_node<'m>(mathml: Element<'m>, nav_state: &RefMut<NavigationState>) -> Result<Element<'m>>  {
        let start_node_id =  match nav_state.top() {
            None => mathml.attribute_value("id").unwrap().to_string(),
            Some( (position, _) ) => position.current_node.clone(),
        };

        return match get_node_by_id(mathml, &start_node_id) {
            Some(node) => Ok(node),
            None => {
                bail!("Internal Error: didn't find id '{}' while attempting to start navigation", &start_node_id);
            }
        };
    }