OptimizelyUserContext for the JavaScript (Node) SDK

interface OptimizelyUserContext {
    // set an attribute for the user
    setAttribute(key: string, value: unknown): void;

    // return user attributes
    getAttributes(): UserAttributes;

    // make a decision about which flag variation the user buckets into for the flag key 
    decide(
      key: string,
      options: OptimizelyDecideOption[] = []
      ): OptimizelyDecision;

    // make decisions about which flag variations the user buckets into for flag keys
    decideForKeys(
      keys: string[],
      options: OptimizelyDecideOption[] = [],
      ): { [key: string]: OptimizelyDecision };

    // make decisions about which flag variations the user buckets into for all flags
    decideAll(
      options: OptimizelyDecideOption[] = []
      ): { [key: string]: OptimizelyDecision };

    // track user event
    trackEvent(eventName: string, eventTags?: EventTags): void;
    
    // Sets the forced decision (variationKey) for a given decision context
    setForcedDecision(context: OptimizelyDecisionContext, decision: OptimizelyForcedDecision): boolean;

    // Returns the forced decision for a given decision context
    getForcedDecision(context: OptimizelyDecisionContext): OptimizelyForcedDecision | null;

    // Removes the forced decision for a given decision context
    removeForcedDecision(context: OptimizelyDecisionContext): boolean;

    // Removes all forced decisions bound to this user context
    removeAllForcedDecisions(): boolean;
  
    //
    // The following methods require the Real-Time Segments for Feature Experimentation. 
    // See note below code sample. 
    //

    // An array of segment names that the user is qualified for. 
    // The result of **fetchQualifiedSegments()** will be saved here. 
    // Can be nil if not properly updated with fetchQualifiedSegments(). 
    // 
    //  You can read and write directly to the qualified segments array. 
    //  This allows for bypassing the remote fetching process from ODP 
    //  or for utilizing your own fetching service.   
    let qualifiedSegments = [];

    // Fetch all qualified segments for the user context. 
    //
    // The segments fetched will be saved in **qualifiedSegments** and can be accessed any time.
    // On failure, **qualifiedSegments** will be nil and one of these errors will be returned:
    // - OptimizelyError.invalidSegmentIdentifier
    // - OptimizelyError.fetchSegmentsFailed(String)
    //
    // - Parameters:
    //   - options: A set of options for fetching qualified segments (optional).
    //   - completionHandler: A completion handler to be called with the fetch result. 
    //     On success, it will pass a non-nil segments array (can be empty) with a nil error. 
    //     On failure, it will pass a non-nil error with a nil segments array.
    fetchQualifiedSegments(options = [], completionHandler) 
  
    //  Check is the user qualified for the given segment. 
    // - Parameter segment: the segment name to check qualification for.
    // - Returns: true if qualified.
    isQualifiedFor(segment)
}