anchor.diff:    (is (equal (list (list 0 1 2 3) (list 4 5 6 7) (list 8 9 10 11))
                (let ((pat (ps (pseries))))
                  (loop :repeat 3
  -                  :collect (next-upto-n pat 4))))
  +                     :collect (next-upto-n pat 4))))
         "ps fails to resume the pstream on subsequent calls to as-pstream"))
  
positive.code:                (let ((pstr (as-pstream (pseq (list 1 2 99) 1))))
                   (list (pstream-elt-future pstr 0)
                         (next pstr))))
          "getting future outputs with pstream-elt-future affects outputs from `next'")))
  
  (test special-wrap-keys ;; FIX: should work for all filter patterns
    "Test behavior of wrap keys"
  
negative.code:                (mapcar (lambda (e) (event-value e :foo)) (next-upto-n pstr 8))))
        "pstream's number is not accessible with pk"))
  
  
  (test next
    "Test next and next-upto-n"
  