     /**
     Convenience initializer.
     
-    :param: block a dispatch block which is run on the main thread.
+    - parameter block: a dispatch block which is run on the main thread.
     */
     public convenience init(mainQueueBlock: dispatch_block_t) {
         self.init(block: { continuation in

        })
    }

    public override func execute() {
        block { error in self.finish(error) }
    }

    /**
    Designated initializer.
    
    - parameter block: The closure to run when the operation executes.
    If this block is nil, the operation will immediately finish.
    */
    public init(block: BlockType = { (continueWithError) in continueWithError(error: nil) }) {
