OnLoadCallback typedef
OnLoadCallback =
Future<void> Function()
A callback function that's invoked when the EasyRefreshSliverLoadControl is
pulled a loadTriggerPullDistance
. Must return a Future. Upon
completion of the Future, the EasyRefreshSliverLoadControl enters the
LoadMode.done state and will start to go away.
Implementation
typedef OnLoadCallback = Future<void> Function();