> # Unnamed vector
> rename_loc(letters, c(foo = a))
Error: Can't rename an unnamed vector.

> # Duplicate names (FIXME)
> rename_loc(mtcars, c(foo = cyl, foo = disp))
Error: Names must be unique.
x These names are duplicated:
  * "foo" at locations 1 and 2.

> # Unnamed inputs
> rename_loc(iris, Species)
Error: All renaming inputs must be named.

