docs: function(node, action, flags) {
          var adj = node.adjacencies, filter = this.filter(flags);
          for(var id in adj) {
            var a = adj[id];
            if(filter(a)) {
              if(a.nodeFrom != node) {
                var tmp = a.nodeFrom;
                a.nodeFrom = a.nodeTo;
                a.nodeTo = tmp;
              }
              action(a, id);
            }
          }
      }