The definition of letfn should use ~@body rather than
~body.
It's simple enough to fix, but in any case, a workaround
is to insert "block" after the function definitions:
(letfn
((tst1 z)
(prn z)
(tst2 x y)
(tst1 (list y x))
)
block ; broken letfn needs this.
(tst1 'A)
(tst2 'C 'B)
)