If the current buffer is unibyte, multibyte strings are converted
to unibyte for insertion.
+If an overlay begins at the insertion point, the inserted text falls
+outside the overlay; if a nonempty overlay ends at the insertion
+point, the inserted text falls inside that overlay.
+
usage: (insert-before-markers &rest ARGS) */)
(ptrdiff_t nargs, Lisp_Object *args)
{