Finding neighbours of links in a graph

For a graph as shown below, how can I list the immediate neighbours as well as neighbours of neighbours of a link

For example, for the link 1-2, the immediate neighbours are 1-3,3-1,2-6,6-2

neighbours of neighbours are 3-4,4-3,3-12,12-3,6-8,8-6,6-5,5-6

Answer 1

[Matt J]

See neighbors.