Toggle legacy compatibility voices in BUFFER.

With a positive prefix ARG, enable them.  With zero or a negative prefix,
disable them.  This does not change semantic presentation or explicit
visual-face presentation rules.

(fn &optional ARG BUFFER)

Toggle the legacy face and personality voice compatibility adapter.

This is a minor mode.  If called interactively, toggle the ‘Voice-Lock
mode’ mode.  If the prefix argument is positive, enable the mode, and if
it is zero or negative, disable the mode.

If called from Lisp, toggle the mode if ARG is ‘toggle’.  Enable the
mode if ARG is nil, omitted, or is a positive number.  Disable the mode
if ARG is a negative number.

To check whether the minor mode is enabled in the current buffer,
evaluate the variable ‘voice-lock-mode’.

The mode’s hook is called both when the mode is enabled and when it is
disabled.

(fn &optional ARG)