add method
- T data
 
override
 Adds event to the controller's stream.
As StreamController.add, but must not be called while an event is being added by add, addError or close.
Implementation
void add(T data);
    © 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
    https://api.dart.dev/stable/2.13.0/dart-async/SynchronousStreamController/add.html