You should use a bracket ({) when defining your container 'group' collection2                                                                                                                           
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                              first                                                                                                                                         
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                        second                                                                                                                                              
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                              fourth                                                                                                                                        
                                                                                                                                                                                                                            
                                                                                                                                                                                                                       third
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                             collection2                                                                                                                                                                                    
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                                                                                                                                                                            
                                                                              fifth