WRITEABLEP

[KMP at MIT-MC (Kent M. Pitman)]

Actually, there is a problem with (DEFUN WRITEABLEP (X) (NOT (PUREP X)))
-- it only works AFTER the PUREP library has been loaded. Otherwise PUREP
autoloads and clobbers the good definition of writeablep. So until things
are fixed, putting 

	(COND ((GET 'WRITEABLEP 'SUBR)
	       (LOAD "LISP:PUREP")))
	(DEFUN WRITEABLEP (X) (NOT (PUREP X)))

is the correct thing to do on a Twenex machine.