anchor.diff:  (-> dict (&rest t) hash-table)
   (-> pophash (t hash-table) (values t boolean))
   (-> swaphash (t t hash-table) (values t boolean))
  -(-> merge-tables (hash-table &rest hash-table) hash-table)
  +(-> merge-tables (hash-table &rest hash-table)
  +    hash-table)
   
   (defconst hash-table-default-size
     (hash-table-size (make-hash-table)))
  
positive.code:                    (reduce #'+ tables
                             :key #'hash-table-count
                             :initial-value (hash-table-count table)))))
      (apply #'merge-tables!
             (copy-hash-table table :size size)
             tables)))
  
  (defun merge-tables! (table &rest tables)
    (reduce (lambda (x y)
  
negative.code:   (let ((test (if (oddp (length keys-and-values))
                    (pop keys-and-values)
                    'equal)))
      (values (plist-hash-table keys-and-values :test test))))
  
  (define-compiler-macro dict (&rest keys-and-values)
    (let ((test (if (oddp (length keys-and-values))
  