Stuck at the 55% completion exercise. Trying to use the evaluate function defined as follows:

evaluate <- function(func, dat){
 func(dat)
}

Stuck at this next exercise:

Let's take your new evaluate() function for a spin! Use evaluate to find the standard deviation of the vector c(1.4,
| 3.6, 7.9, 8.8).

My input is

> evaluate(sd, c(1.4, 3.6, 7.9, 8.8))

I keep getting the error

Error in func(dat) : could not find function "func"

I’ve tried restarting swirl and using the following line of code, but to no avail.

> evaluate(func = sd, dat = c(1.4,3.6,7.9,8.8))

Please help.