def add_musician_to_band(self, musician_name: str, band_name: str):
        current_musicians = []
        current_bands = []
        for musician in self.musicians:
            current_musicians.append(musician.name)
        if musician_name not in current_musicians:
            raise Exception(f"{musician_name} isn't a musician!")

        for band in self.bands:
            current_bands.append(band.name)
        if band_name not in current_bands:
            raise Exception(f"{band_name} isn't a band!")

        for player in self.musicians:
            if player.name == musician_name:
                self.bands.append(player)
                return f"{musician_name} was added to {band_name}."