anchor.diff:      :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)."))
  +  (:documentation "Lookuptable that can hold up to 64 elements, under 64 indexes (from 0 to 63)."))
   
   
   (defmethod print-object ((object fixed-lookuptable) stream)
  
positive.code: 
  (defun alter-mask (index mask)
    (declare (type index index)
             (type (unsigned-byte 32) mask))
    (assert (< index 32))
    (dpb 1 (byte 1 index) mask))
  
  
  
negative.code: (defun apply-mask-to-index (index mask)
    (declare (type index index)
             (type (unsigned-byte 64) mask))
    (assert (< index 64))
    (logcount (ldb (byte index 0) mask)))
  
  
  