static fromConfig(config) {
        if (config === null) return null;
        switch (config.type) {
            case 'BertNormalizer':
                return new BertNormalizer(config);
            case 'Precompiled':
                return new Precompiled(config);
            case 'Sequence':
                return new NormalizerSequence(config);
            case 'Replace':
                return new Replace(config);
            case 'NFC':
                return new NFC(config);
            case 'NFD':
                return new NFD(config);
            case 'NFKC':
                return new NFKC(config);
            case 'NFKD':
                return new NFKD(config);
            case 'Strip':
                return new StripNormalizer(config);
            case 'StripAccents':
                return new StripAccents(config);
            case 'Lowercase':
                return new Lowercase(config);
            case 'Prepend':
                return new Prepend(config);
            default:
                throw new Error(`Unknown Normalizer type: ${config.type}`);
        }
    }
Factory method for creating normalizers from config objects.
@static
@param {Object} config The configuration object for the normalizer.
@returns {Normalizer} A Normalizer object.
@throws {Error} If an unknown Normalizer type is specified in the config.