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: tldDemo.m
    path of file: ./repos/OpenTLD/tld
    
    the code of the file until where you have to start completion: % Copyright 2011 Zdenek
    
function tldDemo(opt)

global tld; % holds all tracking results

select_source = 1;
initialize    = 1;
quit_tld      = 0;

while 1
    
    % select data source --------------------------------------------------
    if select_source
        opt.source = tldInitSource(opt.source);
        select_source = 0;
        initialize    = 1;
        tld           = [];
    end