(mod (Z)

  (include *standard-cl-23*)
  ; takes a lisp tree and returns the hash of it

  (defun sha256tree1 (TREE)
    (if (l TREE)
      (sha256 2 (sha256tree1 (f TREE)) (sha256tree1 (r TREE)))
      (sha256 1 TREE)
      )
    )

  (defconst HELLO_HASH (sha256tree1 (c "hello" "world")))
  
  (sha256 HELLO_HASH Z)
  )