Graph use case for prego

This an use case of library prego. It is a NodeJS application. Hence, to start it, you might:

1. Run on command npm install && npm start
2. Type on URL field localhost:8080

The result rendering depends of browser. Either browser choice, the result must be as below:

{
    "vertices": "A,B,C,D,E,F",
    "edges": "A_B,B_C,C_D,C_E,E_B,C_F,F_B",
    "vertices_keys_to_indices": { "A": 0, "B": 1, "C": 2, "D": 3, "E":4, "F":5 },
    "adjacency_list": { "0": [ 1 ], "1": [ 2 ], "2": [ 3, 4, 5 ], "3": [ ], "4": [ 1 ], "5": [ 1 ] },
    "sink_nodes": [ 3 ],
    "source_nodes": [ 0 ],
    "articulation_nodes": [ 2, 1 ],
    "bridges": [ [ 2, 3 ], [ 0, 1 ] ],
    "is_cyclic": true,
    "all_cycles": [ [ 1, 2, 4 ], [ 1, 2, 5] ],
    "is_eulerian": false,
    "is_connected": true
}