value property
Returns the current value
Implementation
@override
@protected
Map<K, V> get value {
  RxInterface.proxy?.addListener(subject);
  return _value;
}
Updates the value and adds it to the stream, updating the observer Widget, only if it's different from the previous value.
Implementation
set value(T val) {
  if (subject.isClosed) return;
  sentToStream = false;
  if (_value == val && !firstRebuild) return;
  firstRebuild = false;
  _value = val;
  sentToStream = true;
  subject.add(_value);
}