def ask_overwrite(dest):
    """Check if file *dest* exists. If 'True', asks if the user wants
    to overwrite it (just remove the file for later overwrite).
    """

    msg = "File '{}' already exists. Overwrite file?".format(dest)
    if os.path.exists(dest):
        if yes_no_query(msg):
            os.remove(dest)
        else:
            sys.exit("Cancelling operation...")