returns a tuple of total file size in bytes, and the list of files

def get_uris(config):
    """ returns a tuple of total file size in bytes, and the list of files """
    file_names = []
    if config.INPUT_DATA is None:
        sys.stderr.write("you need to provide INPUT_DATA in config\n")
        sys.exit(1)
    if isinstance(config.INPUT_DATA, basestring):
        config.INPUT_DATA = [config.INPUT_DATA]
    file_size = 0
    for uri in config.INPUT_DATA:
        for regex, uri_method, _, _ in URI_REGEXES:
            m = regex.match(uri)
            if m is not None:
                file_size += uri_method(m, file_names, config)
                break
    print("going to process {} files...".format(len(file_names)))
    return file_size, file_names