OptimizelyUserContext for the JavaScript (Browser) SDK prior to v6

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 Real-Time Audiences for Feature Experimentation. 
    // See note following this code sample. 
    //

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

    // Fetch all qualified segments for the user context. 
    //
    // The segments fetched are saved in **qualifiedSegments** and can be accessed any time.
    // On failure, **qualifiedSegments** is nil and one of the following errors are returned:
    // - OptimizelyError.invalidSegmentIdentifier
    // - OptimizelyError.fetchSegmentsFailed(String)
    //
    // - Parameters:
    //   - options – (Optional) A set of options for fetching qualified segments.
    //   - completionHandler – A completion handler to be called with the fetch result. 
    //     On success – Passes a non-nil segments array (can be empty) with a nil error. 
    //     On failure – Passes 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)
}