anchor.diff:  (defun car (x)
     "Return the first element present in the list X. This function operates
      in constant time.
  -   
  +
      Example:
      ```
      > (car '(1 2 3))
  
positive.code:    proportion to the size of the input list. This is generally a bad thing."
  
  (import base (defun defmacro when let* set-idx!
                get-idx cons for gensym -or
                pretty print error tostring  -and
                unpack debug if # + - >= = ! with))
  (import base)
  
negative.code:   (if (nil? x)
      '()
      (base/cdr x)))
  
  (defun take (xs n)
    "Take the first N elements of the list XS.
  
     Example:
     ```
     > (take '(1 2 3 4 5) 2)
     '(1 2)
     ```"
    (slice xs 1 n))
  
  (defun drop (xs n)
    "Remove the first N elements of the list XS.
  
     Example:
     ```
     > (take '(1 2 3 4 5) 2)
     '(3 4 5)
     ```"
    (slice xs n nil))
  
  (defun snoc (xss &xs)
    "Return a copy of the list XS with the element XS added to its end.
  