anchor.diff:        (setf (cdr (assoc key obj)) value)
         (nconc obj (list (cons key value)))))
   
  -(defmethod mset (obj key value)
  +(defgeneric mset (obj key value)
     (:documentation "Return a mapping with value associated with key.  Don't modify the original mapping."))
   
   (defmethod mset ((obj list) key value)
  
positive.code:           `(-> (,(car rest) ,first) ,@(cdr rest)))
        first))
  
  (defmacro rmapcar (lst fn)
    "Mapcar with arguments reversed.  Allows use with threading macro."
    `(mapcar ,fn ,lst))
  
negative.code:   "Shorthand for let for a single binding."
    `(let ((,var ,val))
       ,@body))
  
  (defun <> (&rest strings)
    "Shorthand for concatenating strings."
    (apply #'concatenate (cons 'string strings)))
  