def dijkstra(graph,source,target):
    # initialize "visited" nodes
    # ("visited" nodes keep track of how you got there and the total distance)

    # initialize your "to do list" of nodes
    # (start at the source, got here by starting here, with total distance of 0)

    # while there are nodes in your todo list
        # get the node with the highest priority, i.e., the lowest total distance

        # "visit" it

        # is this node the target?  If so, you're done.
            # return (typically) the path from the source to here, as stored in the "visited" nodes

        # explore the edges from here
        # for each pointed-to node, recompute the total distance, and add/update them in todo list

    # return "I can't get there."