anchor.diff:  (export '(pophash swaphash
             dict dict* @ href href-default
             merge-tables flip-hash-table
  -          maphash-return
  +          hash-fold maphash-return
             set-hash-table hash-table-set))
   
   (-> dict (&rest t) hash-table)
  
positive.code: The resulting hash table has the same test as TABLE.
  
  Clojure's `merge'."
    (let ((size (max hash-table-default-size
                     (reduce #'+ tables
                             :key #'hash-table-count
                             :initial-value (hash-table-count table)))))
  
negative.code: (-> merge-tables (hash-table &rest hash-table)
      hash-table)
  
  (defconstant +hash-table-default-size+
    (hash-table-size (make-hash-table)))
  
  (deftype ok-hash-table-test ()
  