anchor.diff:    (assert-type! f function)
     (assert-type! ac function)
     (foldl ac z (map f xs)))
  +
  +(defun sum (xs)
  +  "Return the sum of all elements in XS.
  +
  +   ### Example:
  +   ```cl
  +   > (sum '(1 2 3 4))
  +   out = 10
  +   ```"
  +  (foldl + 0 xs))
  +
  +(defun prod (xs)
  +  "Return the product of all elements in XS.
  +
  +   ### Example:
  +   ```cl
  +   > (prod '(1 2 3 4))
  +   out = 24
  +   ```"
  +  (foldl * 1 xs))
   
   ;; AUTOMATICALLY GENERATED
   ;; DO NOT EDIT please.
  
positive.code:               get-idx for gensym -or slice /=
                pretty print error tostring  -and
                unpack debug if # + - >= = ! with
                apply and progn ..))
  (import base)
  (import lua/table)
  (import type (nil? list? empty? assert-type! exists? falsey? eq? type))
  
negative.code: (defun union (xs ys)
    "Set-like union of XS and YS.
  
     ### Example:
     ```
     > (union '(1 2 3 4) '(1 2 3 4 5))
     out = (1 2 3 4 5)
  