infer & arbitrary test statistic

tidyverse
1

I'm using infer 1.1.0 and it won't allow me to use an arbitrary test statistic, which is supposed to be a new feature.

trimmed_mean_10 <- function(x, order, ...) {mean(x$Delay, trim=0.10)}

obs_trimmed_mean <- FlightDelays |>
specify(Delay ~ Carrier) |>
calculate(stat=trimmed_mean_10)

gives me

Error in calculate():
! stat must be 'string', not 'closure'.

Am I doing something wrong?