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: CBIG_MMP_plot_ROI2ROI.m
    path of file: ./repos/CBIG/stable_projects/predict_phenotypes/Ooi2022_MMP/generate_figures/feature_importance_figures
    
    the code of the file until where you have to start completion: function CBIG_MMP_plot_ROI2ROI(importance, save_dir, prefix)


    
function CBIG_MMP_plot_ROI2ROI(importance, save_dir, prefix)

% CBIG_MMP_plot_ROI2ROI(importance, save_dir, prefix)
% Creates feature importance plots on network edges. 
%
% Input:
% - importance
% A 79800-length vector with importance values from the 400x400 Schaefer 
% parcellation.
%
% - save_dir
% The directory in which the images should be saved.
%
% - prefix
% The prefix to append to the saved images.
%
% Output: 
% - Images with file name "prefix_roi2roi.png"
% One image will be generated representing feature importance values.
% 
% Written by Leon Ooi and CBIG under MIT license: https://github.com/ThomasYeoLab/CBIG/blob/master/LICENSE.md

% Make sure that there are no NaN, skip if detected
if any(isnan(importance))
    fprintf('NaN detected, unable to plot feature importance. \n')
    return
end

% prepare feature importance vector for plotting
importance_max_norm = importance ./ std(importance); % normalize by std
imp_mat = CBIG_MMP_FC_vector_2_mat(importance_max_norm);
% plot ROI2ROI matrix 
CBIG_PlotCorrMatNetOrder(400, imp_mat, 'Schaefer_Kong17', [-2 2])
% remove colorbar and text and set size
colorbar('hide')
fig_t = findall(gcf,'Type','text');
delete(fig_t)
set(gca, 'Position', [0 0 1 1]) 
set(gcf,'PaperPosition',[0 0 6 6])
saveas(gcf, fullfile(save_dir, strcat(prefix,'_roi2roi.png'))); close(gcf);

end