any :set property that the variable might have (if you want that, use
\\[customize-set-variable] instead).
-With a prefix argument, set VARIABLE to VALUE buffer-locally."
+With a prefix argument, set VARIABLE to VALUE buffer-locally.
+
+When called interactively, the user is prompted for VARIABLE and
+then VALUE. The current value of VARIABLE will be put in the
+minibuffer history so that it can be accessed with `M-n', which
+makes it easier to edit it."
(interactive
(let* ((default-var (variable-at-point))
(var (if (custom-variable-p default-var)