Example code in splice does not run

The example code included in the roxygen2 notes from splice throws an error when this example code is ran. Please refer to 
 ?purrr::splice() 

```r
inputs <- list(arg1 = "a", arg2 = "b")

# splice() concatenates the elements of inputs with arg3
splice(inputs, arg3 = c("c1", "c2")) %>% str()
list(inputs, arg3 = c("c1", "c2")) %>% str()
c(inputs, arg3 = c("c1", "c2")) %>% str()
```
