You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: Prepare_data_Multi_PIE_all.m
    path of file: ./repos/OpenFace/model_training/CCNF/patch_experts/data_preparation/scripts
    
    the code of the file until where you have to start completion: function Prepare_data_Multi_PIE_all()

    % This bit collects all of the multi-pie labels into a single structure for
    % easy access
    labels_root = 'C:\Users\tbaltrus\Dropbox\AAM\test data\MultiPI_AAM/';
    
    % The location of the Multi-PIE data folder
    multi_pie_root = 'D:\MultiPIE/Image_Data/';
    
    multi_pie_labels = CollectMultiPieLabels(labels_root, multi_pie_root);

    %% 
    
    % Make 
    
function [multi_pie_labels] = CollectMultiPieLabels(labels_root, multi_pie_root)

    multi_pie_labels = struct;
    currentLabel = 0;
    left_to_frontal_map = [1, 28;
                        2, 29;
                        3, 30;
                        4, 31;
                        5, 34;
                        6, 36;
                        7, 27;
                        8, 26;
                        9, 25;
                        10,24;
                        11,46;
                        12,45;
                        13,44;
                        14,48;
                        15,47;
                        16,52;
                        17,53;
                        18,54;
                        19,55;
                        20,56;
                        21,57;
                        22,58;
                        23,63;
                        24,64;
                        26,66;
                        27,67;
                        30,9;
                        31,10;
                        32,11;
                        33,12;
                        34,13;
                        35,14;
                        36,15;
                        37,16;
                        38,17;];

    right_to_frontal_map = [1, 28;
                            2, 29;
                            3, 30;
                            4, 31;
                            5, 34;
                            6, 32;
                            7 ,18;
                            8 ,19;
                            9 ,20;
                            10,21;
                            11,37;
                            12,38;
                            13,39;
                            14,41;
                            15,42;
                            16,52;
                            17,51;
                            18,50;
                            19,49;
                            20,60;
                            21,59;
                            22,58;
                            23,63;
                            24,62;
                            26,68;
                            27,67;
                            30, 9;
                            31, 8;
                            32, 7;
                            33, 6;
                            34, 5;
                            35, 4;
                            36, 3;
                            37, 2;
                            38, 1];

    for i=1:4

        labelsDir = sprintf('%sSession%d/', labels_root, i);

        labels = dir([labelsDir '/*.mat']);

        double_label = false;

        for j = 1:numel(labels)
            if(double_label)
                double_label = false;
                continue;
            end