UpdateQuery typedef
        UpdateQuery =
     Map<String, dynamic> ? Function(Map<String, dynamic> ? previousResultData, Map<String, dynamic> ? fetchMoreResultData)
    
    
merge fetchMore result data with earlier result data
Implementation
typedef UpdateQuery = Map<String, dynamic>? Function(
  Map<String, dynamic>? previousResultData,
  Map<String, dynamic>? fetchMoreResultData,
);