LoadMoreCallback typedef
        LoadMoreCallback =
     Future<void>  Function()
    
    
Signature for the function that have no arguments and return no data, but that return a Future to indicate when their work is complete.
See also:
- SfCalendar.loadMoreWidgetBuilder, which matches this signature.
 - SfCalendar, which uses this signature in one of it's callback.
 
Implementation
typedef LoadMoreCallback = Future<void> Function();