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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _rank_cycle_function(self, cycle, function, ranks):
 """Dijkstra's shortest paths algorithm. See also: - http://en.wikipedia.org/wiki/Dijkstra's_algorithm """


        import heapq
        Q = []
        Qd = {}
        p = {}
        visited = set([function])

        ranks[function] = 0
        for call in compat_itervalues(function.calls):
            if call.callee_id != function.id:
                callee = self.functions[call.callee_id]
                if callee.cycle is cycle:
                    ranks[callee] = 1
                    item = [ranks[callee], function, callee]
                    heapq.heappush(Q, item)
                    Qd[callee] = item

        while Q:
            cost, parent, member = heapq.heappop(Q)
            if member not in visited:
                p[member]= parent
                visited.add(member)
                for call in compat_itervalues(member.calls):
                    if call.callee_id != member.id:
                        callee = self.functions[call.callee_id]
                        if callee.cycle is cycle:
                            member_rank = ranks[member]
                            rank = ranks.get(callee)
                            if rank is not None:
                                if rank > 1 + member_rank:
                                    rank = 1 + member_rank
                                    ranks[callee] = rank
                                    Qd_callee = Qd[callee]
                                    Qd_callee[0] = rank
                                    Qd_callee[1] = member
                                    heapq._siftdown(Q, 0, Q.index(Qd_callee))
                            else:
                                rank = 1 + member_rank
                                ranks[callee] = rank
                                item = [rank, member, callee]
                                heapq.heappush(Q, item)
                                Qd[callee] = item