message: Document EnabledIf
diff: @@ -475,6 +475,7 @@ pub enum Expr<C> {
  UnnormalizedLagrangeBasis(i32),
  Pow(Box<Expr<C>>, u64),
  Cache(CacheId, Box<Expr<C>>),
  + /// Expression is conditional on the given feature flag, returns 0 if disabled.
  EnabledIf(FeatureFlag, Box<Expr<C>>),
  }
  