private StringBuilder getDotTreeContent(StringBuilder sb, DecisionTree currentNode, int i){
        if(currentNode.isLeafNode())
            //clase positiva, 1.0 => Maligna. Clase negativa: 2.0 => Benigna
            if(Double.compare(currentNode.decision,1.0) == 0)
                sb.append(String.format("node%d [label=\"Maligna\"];\n", i));
            else
                sb.append(String.format("node%d [label=\"Benigna\"];\n", i));
        else
            sb.append(String.format("node%d [label=\"Att%d\"];\n", i, currentNode.attribute));
            
      int lChild = 2*i;
      int rChild = 2*i + 1;

      if(currentNode.left  != null){
        sb.append(String.format("node%d -> node%d;\n", i, lChild));
        getDotTreeContent(sb, currentNode.left, lChild);
      }
      if(currentNode.right != null){
        sb.append(String.format("node%d -> node%d;\n", i, rChild));
        getDotTreeContent(sb, currentNode.right, rChild);
      }
      return sb;
    }