anchor.diff:          (%href-==? !) (%%%aref hash key)
           (%href-user hash key))
         (%%%aref hash key)))
  -
  -(defun hash-table? (x)
  -  (& (object? x)
  -     (undefined? x.__class)))
   
   (defun hash-merge (a b)
     (when (| a b)
  
positive.code:        (return (%%%aref hash (%href-key !))))))
  
  (defun href (hash key)
    (!? hash.__tre-test
        (?
          (eq #'eq !)   (%%%aref hash (? (object? key)
                                         key.__tre-object-id
  
negative.code:   (in? x #'== #'string== #'number== #'integer==))
  
  (defun =-href (value hash key)
    (!? (%htest hash)
        (? (%href-==? !)
           (%%%=-aref value hash key)
           (=-href-obj value hash key))
  