def _download(filename, working_directory, url_source):
        def _dlProgress(count, blockSize, totalSize):
            if(totalSize != 0):
                percent = float(count * blockSize) / float(totalSize) * 100.0
                sys.stdout.write("\r" "Downloading " + filename + "...%d%%" % percent)
                sys.stdout.flush()
        if sys.version_info[0] == 2:
            from urllib import urlretrieve
        else:
            from urllib.request import urlretrieve
        filepath = os.path.join(working_directory, filename)
        urlretrieve(url_source+filename, filepath, reporthook=_dlProgress)