cancel method
Cancels this operation.
If this operation isCompleted or isCanceled this call is ignored.
Returns the result of the onCancel
callback, if one exists.
Implementation
Future cancel() => _completer._cancel();
Cancels this operation.
If this operation isCompleted or isCanceled this call is ignored.
Returns the result of the onCancel
callback, if one exists.
Future cancel() => _completer._cancel();