def get_script_urls_from_call_stack_as_set(call_stack):
    """Return the urls of the scripts involved in the call stack as a set."""
    script_urls = set()
    if not call_stack:
        return script_urls
    stack_frames = call_stack.strip().split('\n')
    for stack_frame in stack_frames:
        script_url = stack_frame.rsplit(':', 2)[0].split('@')[-1].split(' line'
            )[0]
        script_urls.add(script_url)
    return script_urls
