anchor.diff:  	  %%native %%string
   	  %%closure %closure
   	  %set-atom-fun
  -	  %function-prologue
  -	  %function-epilogue
  -	  %function-return
  +	  %function-prologue %function-return %function-epilogue
         %var %global
         %%comment)
     `(def-head-predicate ,x))
  
positive.code:   (| (lambda? x)
       (named-lambda? x)))
  
  (defun vec-function-expr? (x)
    (& (cons? x)
       (eq x. 'function)
       (%vec? .x.)
       .x.))
  
  (defun metacode-expression? (x)
    (& x
       (| (atom x)
  
negative.code: (defun %=-place (x) .x.)
  (defun %=-value (x) ..x.)
  
  (defun %=-funcall? (x)
    (? (%=? x)
       (cons? (%=-value x))))
  