my path finding function for kirk:
def build_path(
        curr_pos,
        tar_pos,
        values,
        shortest_path_discovered=None,
        curr_sides=None,
        curr_path=None,
        first_call=True,
    ):
    curr_path = curr_path or []
    curr_sides = curr_sides or (UP, DOWN)
    shortest_path_discovered = shortest_path_discovered or [UP] * MAX_MOVES
    values = values.copy()

    if curr_pos == tar_pos:
        return curr_path  # We're here!
    if values[tar_pos] == '?':
        if dist(curr_pos, tar_pos) == 1:  # We got as close as possible to unknown
            return curr_path
    if len(curr_path) > len(shortest_path_discovered):
        return False  # A shorter path was found before

    safe_positions = build_line(curr_pos, values, curr_sides)

#    debug_path_finding(dist=dist(curr_pos, tar_pos), **locals())

    for pos in safe_positions:
        values[pos] = 'W'

    next_sides = (UP, DOWN) if curr_sides[0] == RIGHT else (RIGHT, LEFT)
    for pos in safe_positions:
        if pos == curr_pos and not first_call:
            continue
        path = build_path(
            pos,
            tar_pos,
            values,
            shortest_path_discovered,
            next_sides,
            curr_path + [pos],
            first_call=False,
        )
        if path and len(path) < len(shortest_path_discovered):
            shortest_path_discovered = path
            if dist(curr_pos, tar_pos) >= len(shortest_path_discovered):
                return shortest_path_discovered  # won't get quicker
    if len(shortest_path_discovered) < MAX_MOVES:
        return shortest_path_discovered  # we found a way
    return False