Stubbed out cancel ticket example

cancel_ticket_example.m

PLCancelTicketSet *ticketSet = [PLCancelTicketSet ticketSet];
id<PLCancelTicket> httpTicket = [_client connectionWithRequest: req
                                                      bodyData: reqData
                                                       timeout: timeout
                                               dispatchContext: [PLDirectDispatchContext context]
                                                         block: ^(PLHTTPResponse *response, id <PLInputStream> bodyInputStream, NSError *error)
{
   // ... check for error ..
   PLLimitingInputStreamFilter *inputFilter = [PLLimitingInputStreamFilter filterWithInputStream: bodyInputStream
                                                                                    maximumBytes: MAX_RESOURCE_DOWNLOAD_BYTES];
                                         
    // Asynchronously copy the response body
    PLDataOutputStream *dataStream = [PLDataOutputStream stream];
    id<PLCancelTicket> copy = [PLPipeStream copyInputStream: inputFilter
                                             toOutputStream: dataStream
                                                withTimeout: remaining 
                                            dispatchContext: dispatchContext
                                                      block: ^(NSError *error) {
        if (error != nil) {
            resultBlock(nil, PLExampleClientErrorWithCode(PLExampleClientErrorConnectionLost, error));
            return;
        }
                                                                        
        /* Success -- decode the result */
        NSString *stringResult = [[NSString alloc] initWithData: dataStream.data
                                                       encoding: [response textEncodingWithDefaultEncoding: NSUTF8StringEncoding]];
        resultBlock(stringResult, nil);
    }];
                                         
    /* Add our copy ticket to the cancel ticket set. */
    [ticketSet addCancelTicket: copy];
}

[ticketSet addCancelTicket: httpTicket];
    
return [PLCancelTicket cancelTicketWithBlock: ^{
    /* Cancel the set */
    [ticketSet cancel];
        
    /* Let the result ticket perform cleanup */
    resultBlock(nil, nil);
}];