anchor.diff:    (| (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)
  
positive.code: (defun %=-place (x) .x.)
  (defun %=-value (x) ..x.)
  
  (defun %=-args (x)
    (let v (%=-value x)
      (? (cons? v)
  	   .v
  	   (list v))))
  
  (defun %=-funcall? (x)
    (? (%=? x)
       (cons? (%=-value x))))
  
negative.code: 	  %%native %%string
  	  %%closure %closure
  	  %set-atom-fun
  	  %function-prologue %function-return %function-epilogue
        %var %global
        %%comment)
    `(def-head-predicate ,x))
  