public Collection<Var> migrate(){
  Collection<Var> collection=new HashSet<>();
  for (  Collection<Var> vars : this) {
    collection.addAll(vars);
  }
  return collection;
}

public Collection < Var > migrate ( ) { Collection < Var > collection = new HashSet < > ( ) ; for ( Collection < Var > vars : this ) { collection . addAll ( vars ) ; } return collection ; }
migrate a csv schema into a mindmaps ontology
