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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 parse(self):
 """ Parses the detected alternative :return: An Asn1Value object of the chosen alternative """


        if self._parsed is not None:
            return self._parsed

        try:
            _, spec, params = self._alternatives[self._choice]
            self._parsed, _ = _parse_build(self._contents, spec=spec, spec_params=params)
        except (ValueError, TypeError) as e:
            args = e.args[1:]
            e.args = (e.args[0] + '\n    while parsing %s' % type_name(self),) + args
            raise e