message: making overridden abstract
  implemented by extending classes
diff: @@ -170,7 +170,7 @@ export abstract class AbstractParam<Type extends Unit> {
  * True if the signal value is being overridden by
  * a connected signal. Internal use only.
  */
  - abstract readonly overridden: boolean = false;
  + abstract overridden: boolean;
  /**
  * The minimum value of the output given the units
  