anchor.diff:  
   (test beat-key
     "Test that the :beat key is correct"
  +  (is-true (equal (list 0 1/2 1 3/2)
  +                  (gete (next-n (pbind :dur 1/2
  +                                       :x (pf (beat *event*)))
  +                                4)
  +                        :x))
  +           "event's beat is accessible and correct in basic patterns")
     (is-true (every-event-equal
               (list (event :beat 0)
                     (event :beat 3))
  
positive.code:             (next-upto-n (pbind :beat 2
                                  :embed (pbind :beat (p+ (pk :beat) (pseq '(1 3) 1))
                                                :x (pseries)))))
             ":beat key is accessible in embedded patterns"))
  
  (test pstream-count
    "Test `pstream-count' functionality"
  
negative.code:   (is (equal
         (list 0 1 2 3 4 5 nil)
         (next-n (pseq (list 0 (pseq (list 1 (pseq (list 2 3) 1) 4) 1) 5) 1) 7))
        "Stacked pseqs give correct results")
    (is-true (equal (list 0 0 0 1 1 1 2 2)
                    (gete
                     (next-n
                      (pbind :foo 3
                             :embed (pr (pbind :inner (pseries))
                                        (pk :foo)))
                      8)
                     :inner))
             "Embedded patterns can access event values from their parent pattern."))
  
  (test number-key
    "Test the number key in patterns and pstreams"
  