Hi,

From 9.10 ARIMA vs ETS | Forecasting: Principles and Practice (3rd ed) (otexts.com)

After estimating an ARIMA model in fable, how do I extract the model degrees of freedom (to match the number of parameters in the model) without inputting dof manually, as in?

```
cement <- aus_production |>
select(Cement) |>
filter_index("1988 Q1" ~ .)
train <- cement |> filter_index(. ~ "2007 Q4")
fit_arima <- train |> model(ARIMA(Cement, trace = TRUE))
report(fit_arima)
augment(fit_arima) |>
features(.innov, ljung_box, lag = 16, dof = ?)
```

thanks,

Amarjit