type YesNo = 'YES' | 'NO'; type PassFailUnknown = 'PASS' | 'FAIL' | 'UNKNOWN'; export const toYesNo = (value: boolean): YesNo => { return value ? 'YES' : 'NO'; }; export const toPassFail = (value: boolean): PassFailUnknown => { return value ? 'PASS' : 'FAIL'; };