@interface NSArray (AGPagedList)
@property id<NSObject> pipe; // try to NOT expose it..... (e.g. internal category?)


/**
 * Reads the next 'page', based on the current position, of the paging result, from the server.
 *
 * @param success A block object to be executed when the request operation finishes successfully.
 * This block has no return value and takes one argument: The object created from the response
 * data of request.
 *
 * @param failure A block object to be executed when the request operation finishes unsuccessfully,
 * or that finishes successfully, but encountered an error while parsing the resonse data.
 * This block has no return value and takes one argument: The `NSError` object describing
 * the network or parsing error that occurred.
 */
-(void) next:(void (^)(id responseObject))success
     failure:(void (^)(NSError *error))failure;
/**

 * Reads the previous 'page', based on the current position, of the paging result, from the server.
 *
 * @param success A block object to be executed when the request operation finishes successfully.
 * This block has no return value and takes one argument: The object created from the response
 * data of request.
 *
 * @param failure A block object to be executed when the request operation finishes unsuccessfully,
 * or that finishes successfully, but encountered an error while parsing the resonse data.
 * This block has no return value and takes one argument: The `NSError` object describing
 * the network or parsing error that occurred.
 */
-(void) previous:(void (^)(id responseObject))success
     failure:(void (^)(NSError *error))failure;