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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 GET(self):
 """ The QUERY_STRING parsed into a MultiDict. Keys and values are strings. Multiple values per key are possible. See MultiDict for details. """

        if self._GET is None:
            data = parse_qs(self.query_string, keep_blank_values=True)
            self._GET = MultiDict()
            for key, values in data.iteritems():
                for value in values:
                    self._GET[key] = value
        return self._GET