code: def accessibility(graph):
      
      recursionlimit = getrecursionlimit()
      setrecursionlimit(max(len(graph.nodes())*2,recursionlimit))
      
      accessibility = {}        # Accessibility matrix
  
      # For each node i, mark each node j if that exists a path from i to j.
      for each in graph:
          access = {}
          # Perform DFS to explore all reachable nodes
          _dfs(graph, access, 1, each)
          accessibility[each] = list(access.keys())
      
      setrecursionlimit(recursionlimit)
      return accessibility
docs: Accessibility matrix (transitive closure).
  
      @type  graph: graph, digraph, hypergraph
      @param graph: Graph.
  
      @rtype:  dictionary
      @return: Accessibility information for each node.