This would examine the immediate neighbors of the target node, hiding those that have degree 1 (i.e., nodes whose only neighbor is the target node). This would be the inverse of an "expand" operation on the same node, assuming no other operations occur in between (e.g., expanding node A to B and C, then expanding node C to D would mean that collapsing A would now only hide B, rather than B and C - without the intervening "expand C" operation, B and C would both be hidden).
This would examine the immediate neighbors of the target node, hiding those that have degree 1 (i.e., nodes whose only neighbor is the target node). This would be the inverse of an "expand" operation on the same node, assuming no other operations occur in between (e.g., expanding node A to B and C, then expanding node C to D would mean that collapsing A would now only hide B, rather than B and C - without the intervening "expand C" operation, B and C would both be hidden).