anchor.diff:  (defun %=-funcall-of? (x name)                                                                                                                                             
     (& (%=-funcall? x)
        (eq name (car (%=-value x)))))
  -
  -(defun %slot-value-obj (x)
  -  .x.)
  -
  -(defun %slot-value-slot (x)
  -  ..x.)
   
   (defun has-return-value? (x)
     (not (| (vm-jump? x)
  
positive.code: 	  %%native %%string
  	  %%closure %closure
  	  %set-atom-fun
  	  %function-prologue
  	  %function-epilogue
  	  %function-return
        %var %global
        %%comment)
    `(def-head-predicate ,x))
  
negative.code: (defun %=-place (x) .x.)
  (defun %=-value (x) ..x.)
  
  (defun %=-funcall? (x)
    (? (%=? x)
       (cons? (%=-value x))))
  