Get code working again

strings.Rmd

@@ -1056,6 +1056,10 @@ So far you've learned how to tidy `table2`, `table4a`, and `table4b`, but not `t
 To fix this problem, we'll need the `separate()` function.
 You'll also learn about the complement of `separate()`: `unite()`, which you use if a single variable is spread across multiple columns.
 
+```{r}
+library(tidyr)
+```
+
 ### Separate
 
 `separate()` pulls apart one column into multiple columns, by splitting wherever a separator character appears.