Construct the sm_match_dict.

        Reverse the key value structure. The sm_match_dict is bigger,
        but allows for direct matching using a dictionary key access.
        The sound_mode_dict is uses externally to set this dictionary
        because that has a nicer syntax.

def construct_sm_match_dict(self):
        """
        Construct the sm_match_dict.

        Reverse the key value structure. The sm_match_dict is bigger,
        but allows for direct matching using a dictionary key access.
        The sound_mode_dict is uses externally to set this dictionary
        because that has a nicer syntax.
        """
        mode_dict = list(self._sound_mode_dict.items())
        match_mode_dict = {}
        for matched_mode, sublist in mode_dict:
            for raw_mode in sublist:
                match_mode_dict[raw_mode.upper()] = matched_mode
        return match_mode_dict