@Override
 public boolean targetUnchanged() {
   for (ProvaVariable var : targetVariables) {
     if (var.getAssigned() != null
         && (!(var.getAssigned() instanceof ProvaVariable)
             || var.getType() != ((ProvaVariable) var.getAssigned()).getType())) return false;
   }
   return true;
 }
 private boolean isSourceSubstituted() {
   for (ProvaVariable variable : sourceVariables) if (variable.getAssigned() != null) return true;
   return false;
 }