def code_h_format(what):
    """
    Converts content of code/pictures history to an html form
    
    Minor Tweak: You can change the html tags however you like.
    Another Tweak: Can change the length of displayed history (100 currently)
    """
    if len(what) == 0:
        return ''
    res = '<ul>'
    # pick the last 100 (note deque does not support [-100:] slicing)
    for lines in (what[-1-x] for x in range(100) if len(what)>x):
        res += '<li><pre><code>'
        res += lines
        res += '</code></pre></li>'
    res += '</ul>'
    return res