 
     updatePackageSelectionFor = (nodes)->
       # get all packages for these nodes
-      packages = _.chain(nodes).
+      packages = _(nodes).
         map( (n) ->
           if $scope.node[n]? and $scope.node[n].packages
             ( p.id for p in $scope.node[n].packages )


    updateNodeSelectionFor = (packages)->
      # get all package ids for the list of package names
      pids = _.chain(packages).
        # first we get all versions for this package name
        map( (p)-> $scope.packageByName[p].versions ).
        flatten().

        map( (v)-> v.id ).
        value()
      # get all nodes for the selected packages
      nodes = _(pids).
        map( (pid)->
          if $scope.package[pid]? and $scope.package[pid].nodes
            ( n.id for n in $scope.package[pid].nodes )
