anchor.diff:      :reader read-container
       :initarg :container)
      (%mask
  -    :type integer
  +    :type (unsigned-byte 64)
       :initarg :mask
       :reader read-mask))
     (:documentation "Lookuptable that can hold up to 32 elements, under 32 indexes (from 0 to 31)."))
  
positive.code: 
  (defun apply-mask-to-index (index mask)
    (declare (type index index)
             (type (unsigned-byte 32) mask))
    (assert (< index 32))
    (logcount (ldb (byte index 0) mask)))
  
  
negative.code:   ((%replacer
      :type vector-replacer
      :initarg :replacer
      :reader read-replacer)))
  
  
  @export
  