(examples-for tuples
  ("returns nil for nil"
   (tuples 3 nil)
   nil)

  ("returns single list for fewer than n items"
   (tuples 4 '(a b) )
   ((a b nil nil)))

  ("returns exactly one list for exactly n items"
   (tuples 5 '(a b c d e) )
   ((a b c d e)))

  ("returns the given list split into sublist each having n items"
   (tuples 3 '(a b c d e f g) )
   ((a b c) (d e f) (g nil nil))))