+(defun make-list (size &key (initial-element nil))
+ "Create a list of size `size` of `initial-element`s."
+ (when (< size 0)
+ (error "Size must be non-negative"))
+ (let ((newlist))
+ (do ((i 0))
+ ((= i size))
+ (push initial-element newlist)
+ (incf i))
+ newlist))
+