anchor.diff:    (let ((test-form (test form)))
       (typecase test-form
         (ast-let
  -       (when (find-if (lambda (x) (typep x 'special-variable))
  -                      (bindings test-form)
  -                      :key #'first)
  +       (when (let-binds-special-variable-p test-form)
            (return-from hoist-form-out-of-if nil))
          (ast `(let ,(bindings test-form)
                  (if ,(body test-form)
  
positive.code:                      (let ((,variable ,(first (last (ast-forms initform))))
                             ,@(subseq (bindings form) (1+ binding-position)))
                         ,(ast-body form))))))
         when (typep initform 'ast-let)
         do
           (change-made)
           (return-from simp-form
  
negative.code:                        ,(first (last (ast-forms arg)))
                         ,@(subseq (arguments form) (1+ arg-position))))))
       when (and (typep arg 'ast-let)
                 (not (let-binds-special-variable-p arg)))
       do
         (change-made)
         (return-from simp-form
  