anchor.diff:  
   (mac awhen (expr &body body)
      "Analog of alf but for when"
  -  `(let1 it ,expr (lf it (progn ,@body)))) ; change name of progn
  +  `(whenlet it ,expr ,@body))
   
   (mac aand (&rest args)
     "Evaluates each argument one by one. Binds the result of the previous
  
positive.code:   (set-macro-character #\] (get-macro-character #\)))
    (set-macro-character #\[
      (fn (stream char)
  	`(fn (_) (,@(read-delimited-list #\] stream t))))))
  
  (def single (xs)
  
negative.code:   (zerop (mod x y)))
  
  ;;; iteration macros to avoid using loop directly
  (mac repeat (times &body body)
    `(loop repeat ,times do (progn ,@body)))
  
  (mac up (var a b &body body)
    "Evaluates body iterating from a up to b inclusive"
    `(loop for ,var from ,a to ,b do (progn ,@body)))
  