param operatorName returns export default function isBuiltInOperatorName ( operatorName ) { return knownBuiltInOperatorNames . includes ( operatorName ) ; } see https export const knownBuiltInOperatorNames = [ 'audit' , 'auditTime' , 'buffer' , 'bufferCount' , 'bufferTime' , 'bufferToggle' , 'bufferWhen' , 'catchError' , 'combineLatest' , 'combineLatestAll' , 'combineLatestWith' , 'concat' , 'concatAll' , 'concatMap' , 'concatMapTo' , 'concatWith' , 'connect' , 'count' , 'debounce' , 'debounceTime' , 'defaultIfEmpty' , 'delay' , 'delayWhen' , 'dematerialize' , 'distinct' , 'distinctUntilChanged' , 'distinctUntilKeyChanged' , 'elementAt' , 'endWith' , 'every' , 'exhaustAll' , 'exhaustMap' , 'expand' , 'filter' , 'finalize' , 'find' , 'findIndex' , 'first' , 'groupBy' , 'ignoreElements' , 'isEmpty' , 'last' , 'map' , 'mapTo' , 'materialize' , 'max' , 'merge' , 'mergeAll' , 'mergeMap' , 'mergeMapTo' , 'mergeScan' , 'mergeWith' , 'min' , 'multicast' , 'observeOn' , 'onErrorResumeNext' , 'pairwise' , 'partition' , 'pluck' , 'publish' , 'publishBehavior' , 'publishLast' , 'publishReplay' , 'race' , 'raceWith' , 'reduce' , 'refCount' , 'repeat' , 'repeatWhen' , 'retry' , 'retryWhen' , 'sample' , 'sampleTime' , 'scan' , 'sequenceEqual' , 'share' , 'shareReplay' , 'single' , 'skip' , 'skipLast' , 'skipUntil' , 'skipWhile' , 'startWith' , 'subscribeOn' , 'switchAll' , 'switchMap' , 'switchMapTo' , 'switchScan' , 'take' , 'takeLast' , 'takeUntil' , 'takeWhile' , 'tap' , 'throttle' , 'throttleTime' , 'throwIfEmpty' , 'timeInterval' , 'timeout' , 'timeoutWith' , 'timestamp' , 'toArray' , 'window' , 'windowCount' , 'windowTime' , 'windowToggle' , 'windowWhen' , 'withLatestFrom' , 'zip' , 'zipAll' , 'zipWith ' , ] ;