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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def update_cnt(uid, post_data):
        '''
        Update the content by ID.
        '''
        entry = TabPostHist.update(
            user_name=post_data['user_name'],
            cnt_md=tornado.escape.xhtml_escape(post_data['cnt_md']),
            time_update=tools.timestamp(),
        ).where(TabPostHist.uid == uid)
        entry.execute()