anchor.diff:  
   (defun event-backends (event)
     "Get a list of backends that EVENT should be played on, either via the event's :backend key or via the `enabled-backends'."
  -  (or (ensure-list (or (event-value event :backends)
  -                       (event-value event :backend)))
  +  (or (ensure-list (or (event-value event :backend)
  +                       (event-value event :backends)))
         (enabled-backends)))
   
   ;;; backend management
  
positive.code: 
  (defun lookup-object-for-symbol (symbol)
    "Look up the object named by SYMBOL using `*dictionary-lookup-functions*'. Returns nil if no object was found."
    (loop :for func :in *dictionary-lookup-functions*
       :for res = (ignore-errors (funcall func symbol))
       :when res
       :return res))
  
  (defun task-nodes (task backend)
    "Get the list of nodes for TASK for the specified backend. If BACKEND is nil, get all of the resources for TASK regardless of backend."
  
negative.code:   "Get a list of all registered backends.
  
  See also: `enabled-backends'"
    *backends*)
  
  (defun enabled-backends ()
    "Get a list of all enabled backends.
  