Function shortest_path_position 

pub fn shortest_path_position<P, G, F>(
    start: Position,
    goal_fn: &P,
    cost_fn: G,
    heuristic_fn: &F,
) -> AStarSearchResults<Position, u32>
where
    P: Fn(Position) -> bool,
    G: Fn(Position) -> Option<u32>,
    F: Fn(Position) -> u32,

Convenience method for running single-start A* with default costs while still retaining control over the heuristic function used.

Note: This function assumes that the heuristic function is consistent, and optimizes accordingly. If your heuristic function is admissible but not consistent, then you risk getting suboptimal paths, just like if your heuristic function is not admissible.