def prune_stat(root, nodes, examples)


    nodes.each_index { | i |

        if nodes[i].leaf then
            next
        end

        # otherwise check if can be pruned
        check_prune = false
        nodes[i].children.each_index{ | j |
            if nodes[i].children[j].leaf then

                check_prune = true
            end
        }


        total = 0
        if check_prune then
            puts "HJERE"
            if(nodes[i].npos == 0 and nodes[i].nneg == 0 ) then
                puts "UNEXPECTED ERROR"
                a = gets.chomp!
            end

            size = nodes[i].npos  +  nodes[i].nneg


            nodes[i].children.each_index{ | j |

                sum = 0
                p = nodes[i].children[j].npos + nodes[i].children[j].nneg
                p = (1.0 * p  )/ size

                p =
                sum += ( ( nodes[i].children[j].npos - p * node[i].npos )**2 ) / (p * node[i].npos)
                sum += ( ( nodes[i].children[j].nneg - p * node[i].nneg )**2 ) / (p * node[i].nneg )

                total += sum
            }


           if total < THRESHOLD then
                nodes[i].leaf = true
                nodes[i].label = nodes[i].most_common

                puts "PRUNED"

                correct = total = acc = 0
                            examples.each_index{ | k |
                                                                classification = report_acc( root, examples[k] )

                                                                if( examples[i].label == classification ) then
                                                                    correct += 1
                                                                end

                                                                total += 1

                                                            }

                            acc = (1.0 * correct) / ( total )
                print acc
                puts

                return true
           end


        end

        return false
    }


end