323             h = [(-dist[node], node)]

   323             h = [(-dist[node], node)]

   324             seen = {}

   324             seen = {}

   325             earliest = self.count()

   325             earliest = self.count()

   326             while h:

   326             while h:

   327                 d, n = heapq.heappop(h)

   327                 d, n = heapq.heappop(h)

   329                 if n not in seen:

   328                 if n not in seen:

   330                     seen[n] = 1

   329                     seen[n] = 1

   332                     for p in self.parents(n):

   332                     for p in self.parents(n):

   333                         heapq.heappush(h, (-dist[p], p))

   333                         heapq.heappush(h, (-dist[p], p))

   334 

   334 

   335         x = ancestors(a)

   335         x = ancestors(a)

   336         y = ancestors(b)

   336         y = ancestors(b)

   339 

   339 

   340         # increment each ancestor list until it is closer to root than

   340         # increment each ancestor list until it is closer to root than

   341         # the other, or they match

   341         # the other, or they match

   342         while 1:

   342         while 1:

   343             if lx == ly:

   343             if lx == ly:

   345             elif lx < ly:

   345             elif lx < ly:

   346                 ly = y.next()

   346                 ly = y.next()

   347             elif lx > ly:

   347             elif lx > ly:

   348                 lx = x.next()

   348                 lx = x.next()

   349 

   349