code: def _identify_eds_ing(first, second):
          
          A = set([first.L, first.R])
          A.update(first.D)
  
          B = set([second.L, second.R])
          B.update(second.D)
  
          depend_set = A & B
          left, right = sorted(list(A ^ B))
  
          return left, right, depend_set
docs: Find nodes connecting adjacent edges.
  
          Args:
              first(Edge): Edge object representing the first edge.
              second(Edge): Edge object representing the second edge.
  
          Returns:
              tuple[int, int, set[int]]: The first two values represent left and right node
                  indicies of the new edge. The third value is the new dependence set.