get all edges in graph

Do bfs on graph (dfs does not work). Corner case is when a node has an edge to itself.

//example

1 - 2  5
| X | /
3 - 4--
    |_|

edges:
1-2, 1-3, 1-4
2-3, 2-4
3-4
4-4, 4-5

graph:
    id
    set{node} nodes

node:
    id
    set{node} neighbors

(graph):
    edges = new //list{tuple{node, node}}
    visited = new //set
    q = new
    for node in graph.nodes:
        if visited.has(node):
            continue
        q.enqueue(node)
        while !q.isempty():
            node = q.dequeue()
            if visited.has(node):
                continue
            for neighbor in node.neighbors:
                if visited.has(neighbor):
                    continue
                q.enqueue(neighbor)
                edges.add(tuple(node, neighbor))
            // corner case: node could have edge to itself, 
            // so mark it visited after visiting its neighbors
            visited.add(node)
    return edges