   /// - parameter value: the value to be validated
 
   public func validate(qos: DispatchQoS,
-                             predicate: @escaping (_ value: Value) throws -> Void) -> Deferred
+                       predicate: @escaping (_ value: Value) throws -> Void) -> Deferred
   {
     let queue = DispatchQueue(label: "deferred", qos: qos)
     return validate(queue: queue, predicate: predicate)

  /// - parameter value: the value to be validated

  public func validate(qos: DispatchQoS,
                             predicate: @escaping (_ value: Value) -> Bool, message: String = "") -> Deferred
  {
    let queue = DispatchQueue(label: "deferred", qos: qos)
    return validate(queue: queue, predicate: predicate, message: message)

  /// - parameter value: the value to be validated

  public func validate(queue: DispatchQueue? = nil,
                       predicate: @escaping (_ value: Value) throws -> Void) -> Deferred
  {
    return self.map(queue: queue) {
      value in
