anchor.diff:     (initial-element :initform nil :initarg :initial-element
                       :documentation "When supplied and no initial-contents supplied, iteration returns the value instead of the index")
      (bound-check :initform #'<= :initarg :from-end
  -                :documentation "When T, direction of iteration is from-endd")
  +                :documentation "When T, direction of iteration is from-end")
      (comparer :initform #'nth
                :documentation "Function to access to individual members of a initial-contents, #'nth for lists, #'elt for others")))
   
  
positive.code: 
  (defmacro make-iterator (&key (start 0) (length -1) (inc 1) (id #'identity) (cyclic nil)
                             (initial-contents ()) (from-end nil) (initial-element nil))
    `(let ((tmp (make-instance 'iterator :start ,start
                               :length (if (null ,initial-contents)
                                           ,length
                                           (1- (length ,initial-contents)))
  
negative.code:            :do-sequence-iterators
             :do-sequence-iterators*
             :dosequences*
             :dosequence
             :list-to-alist))
  
  (in-package :cl-iterators)
  
  