     private let deferred: Deferred<ResultType>
     
     // MARK:- Public properties
-    
+
+    /// Value of Future
     public private(set) var value: ResultType? {
         set {
             deferred.setValue(newValue!)

            return deferred.value
        }
    }
    
    public var isCompleted: Bool {
        return deferred.isCompleted
    }

        }
    }
    
    /**

        Register a callback which will be called when Future is completed with error

        :param: ec execution context of callback
        :param: c callback

        :returns: Returns itself for chaining operations
        
    */
    public func onError(ec: ExecutionContextType, _ c: ErrorCallback) -> Future {
        return onComplete(ec) {
            switch $0 {
