anchor.diff:    (:documentation "A pbind associates keys with values for a pattern stream that returns events."))
   
   (defun pbind (&rest pairs)
  -  "Create an instance of the PBIND class."
     (assert (evenp (length pairs)) (pairs))
     (let ((res-pairs nil)
           (pattern (make-instance 'pbind)))
  
positive.code:   "A pfunc returns the result of the provided function FUNC.")
  
  (defun pfunc (func)
    "Create an instance of the PFUNC class."
    (make-instance 'pfunc
                   :func func))
  
  
negative.code:   "A pk returns a value from the current *event* context, returning DEFAULT if that value is nil.")
  
  (defun pk (key &optional (default 1))
    (make-instance 'pk
                   :key key
                   :default default))
  