### Adding a loop to graph

I have a for loop that adds edges to a graph `g`

, but I also want the graph to add loops. How can I do this, for a general graph whose structure I do not know (that is, I want to add the loop to a graph, rather than make a new graph)?

I've tried using the `g.add_edge(1,1)`

function, but that doesn't work, i.e. no loop is added. I also tried using `g.add_edge`

~~function, ~~three times, then `g.merge_vertices`

to contract ~~a ~~the cycle to a loop, but also to no avail. Sage justs simplifies the graph.

Any approach to this would be appreciated, direct or indirect.