anchor.diff:  
   mk_filter_plus_to(Drai, Filter) ->
   	fun (Id, Set) -> filter_plus_to(Filter, dict:fetch(Id, Drai#drai.darcs), Set) end.
  +mk_filter_plus_from(Drai, Filter) ->
  +	fun (Id, Set) -> filter_plus_from(Filter, dict:fetch(Id, Drai#drai.darcs), Set) end.
   
   filter_plus_to(Filter, Arc, Set) ->
   	case Filter(Arc) of
  
positive.code: % We keep an alternative dict with parent -> child dict (Deps) and a set of covered nodes (Deps)
  -spec expand_cluster(#drai{}, [#diagram_node{}]) -> {sets:set(string()), dict:dict(string(), sets:set(string()))}.
  expand_cluster(Drai, NodeList) ->
    expand_cluster_aux(Drai, NodeList, sets:from_list(get_nod_ids(NodeList)), dict:new()).
  expand_cluster_aux(_Drai, [], Nodes, Deps) -> {Nodes, Deps};
  expand_cluster_aux(Drai, [#diagram_node{id = Id} = Node|Rest], Nodes, Deps) ->
  	ValidChildren = expand_cluster_expand_one_aux(Drai, Id, Nodes, get_cluster_id(Node)),
  
negative.code: % We find children nodes that are not in the set and are in the same cluster as the parent
  -spec expand_cluster_expand_one_aux(#drai{}, string(), sets:set(string()), any()) -> sets:set(string()).
  expand_cluster_expand_one_aux(Drai, Id, Nodes, Cluster) ->
      RawChildrenSet = dia_utils:expand_diamonds_down(Drai, dia_utils:expand_nodes_down(sets:from_list([Id]), Drai)),
      ChildrenSet = sets:subtract(RawChildrenSet, Nodes),
      sets:filter(fun_in_cluster(Drai, Cluster), ChildrenSet).
  
  % Produces a function that takes a node id and returns true iif the node is in the cluster Cluster
  -spec fun_in_cluster(#drai{}, any()) -> fun((string()) -> (boolean())).
  fun_in_cluster(Drai, Cluster) ->
      fun (Id) -> case dict:find(Id, Drai#drai.dnodes) of
  		    {ok, Node} -> get_cluster_id(Node) =:= Cluster;
  		    _ -> false
  		end
      end.
  
  % Adds the set of ValidChildren to the dict of (parent -> set(children)), where both parent and children are nodeIds
  -spec add_to_deps(string(), sets:set(string()), dict:dict(string(), sets:set(string()))) -> dict:dict(string(), sets:set(string())).
  