Dear Liao,
    How are you these days? I am so pleased that I have chance to get your Git and python tutorial. I hope you know how I appreciate your help.
    I think the tutorial you write is so simply ,clear and cool. your are really a good teacher, I can learn this skill very efficiently. After learn this skill I have a strong desire to do sth helpful for the open source community. 
    Thank you for you many kindness and I wish you are happy everyday.
    Sincerely yours,
    Alvin