def colourful_text(text, color):
    """add color to text

    Args:
        text (str): [description]
        color (str): red, green, yellow, blue, black, none

    Returns:
        str: coloured text

    Examples:
        >>> s = String()
        >>> s.colourful_text("比如Convolutional Neural Network，CNN对应中文是卷积神经网络。", "red")
        '\x1b[31m比如Convolutional Neural Network，CNN对应中文是卷积神经网络。\x1b[0m'
    """
    colourful = {
        "red": u"\033[1;31;1m%s\033[0m",
        "green": u"\033[1;32;1m%s\033[0m",
        "yellow": u"\033[1;33;1m%s\033[0m",
        "blue": u"\033[1;34;1m%s\033[0m",
        "black": u"\033[1;30;1m%s\033[0m",
    }
    return colourful[color] % text if color != "none" else text