Toggle CRiSP/Brief emulation (CRiSP mode).
With a prefix argument ARG, enable CRiSP 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)
Track status of CRiSP emulation mode.
A value of nil means CRiSP mode is not enabled. A value of t
indicates CRiSP mode is enabled.
Setting this variable directly does not take effect;
use either M-x customize or the function `crisp-mode'.