src/vs/workbench/services/languageDetection/browser/languageDetectionSimpleWorker.ts/LanguageDetectionSimpleWorker/runRegexpModel
class LanguageDetectionSimpleWorker:	private async runRegexpModel(content: string, langBiases: Record<string, number>, supportedLangs?: string[]): Promise<string | undefined> {
		const regexpModel = await this.getRegexpModel();
		if (!regexpModel) { return; }

		if (supportedLangs?.length) {
			// When using supportedLangs, normally computed biases are too extreme. Just use a "bitmask" of sorts.
			for (const lang of Object.keys(langBiases)) {
				if (supportedLangs.includes(lang)) {
					langBiases[lang] = 1;
				} else {
					langBiases[lang] = 0;
				}
			}
		}

		const detected = regexpModel.detect(content, langBiases, supportedLangs);
		return detected;
	}