<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def entity_to_unicode(string):
 """ Quick convert unicode HTML entities to unicode characters using a regular expression replacement """

    # Selected character replacements that have been seen
    replacements = []
    replacements.append((r"&alpha;", u"\u03b1"))
    replacements.append((r"&beta;", u"\u03b2"))
    replacements.append((r"&gamma;", u"\u03b3"))
    replacements.append((r"&delta;", u"\u03b4"))
    replacements.append((r"&epsilon;", u"\u03b5"))
    replacements.append((r"&ordm;", u"\u00ba"))
    replacements.append((r"&iuml;", u"\u00cf"))
    replacements.append((r"&ldquo;", '"'))
    replacements.append((r"&rdquo;", '"'))

    # First, replace numeric entities with unicode
    string = re.sub(r"&#x(....);", repl, string)
    # Second, replace some specific entities specified in the list
    for entity, replacement in replacements:
        string = re.sub(entity, replacement, string)
    return string