operator == method
This equality override works for _RxImpl instances and the internal values.
Implementation
@override
// ignore: avoid_equals_and_hash_code_on_mutable_classes
bool operator ==(Object o) {
  // Todo, find a common implementation for the hashCode of different Types.
  if (o is T) return value == o;
  if (o is RxObjectMixin<T>) return value == o.value;
  return false;
}