Function: icomplete-mode

Toggle incremental minibuffer completion (Icomplete mode).
With a prefix argument ARG, enable Icomplete mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

(fn &optional ARG)

Variable: icomplete-mode

Non-nil if Icomplete mode is enabled.
See the command `icomplete-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `icomplete-mode'.