def _to_line(title_dict, margin=1):
    """Convert to line.

    Convert to ruled line from each title info.

    Args:
        title_dict (dict): Each title info.
        margin (int): Margin of each table column.

    Returns:
        str: Ruled line.

    """
    line = '+'
    for value in title_dict.values():
        line += ('-' * (margin + value + margin)) + '+'
    return line