code: def parse(self):
          
  
          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
docs: Parses the detected alternative
  
          :return:
              An Asn1Value object of the chosen alternative