     guard let lhs = lhs else {
         return false
     }
-    
+
     return lhs.equals(rhs)
 }

    /// Invokes each registered observer.
    open func notify() {
        flatten()
        observers.forEach { $0.handler?() }
    }
}


    // MARK: Notify API

    /// A boolean property to suppress notifications and This flag value is checked
    /// before firing any notification calls to the registered observers.
    /// The default value is `false`, meaning all notifications will be fired.
    open var suppressNotifications: Bool = false

    /// Invokes each registered observer if `oldValue` is different than `newValue`.
    open func notifyIfNeeded<T: Equatable>(_ oldValue: T, newValue: T) {
        guard oldValue != newValue else { return }
