anchor.diff:  
   ;;;;; MOVING ARGUMENTS
   
  -(defun expex-move-atom (x)
  -  (alet (expex-add-var)
  -    (. (expex-make-%= ! x) !)))
  -
   (defun expex-move-inline (x)
     (with ((p a) (expex-move-args x))
   	(. p a)))
  
positive.code: (defun expex-move (x)
    (pcase x
  	unexpex-able?     (. nil x)
      atom              (expex-move-atom x)
  	expex-inlinable?  (expex-move-inline x)
      %%block?          (expex-move-%%block x)
  	(expex-move-std x)))
  
negative.code:       named-lambda?  (expex-lambda x)
        %%block?       (values nil (expex-body (%%block-body x)))
        unexpex-able?  (values nil (list x))
        (with ((moved new-expr) (expex-move-args (expex-argexpand x)))
          (values moved (list new-expr))))))
  
  
  ;;;; BODY EXPANSION
  