anchor.diff:             :initarg :strand
              :initform 0
              :type (integer -1 1)
  -	   :documentation "The direction in which the feature is found on the genome, if applicable. The number 1 denotes the direction from the small chromosomal arm (p like petit) to the larger (q)."))
  -  (:documentation "Nucleotide sequences can be retrieved from genomic databases (like Ensembl) which is implemented in CBCL. From Ensembl, nucleotides can also be retrieved as genes (with exons and introns) or transcripts. Specialised databases offer information on expressed sequence tags (ESTs)."))
  +	   :documentation "The direction in which the feature is found
  +on the genome, if applicable. The number 1 denotes the direction from
  +the small chromosomal arm (p like petit) to the larger (q)."))
  +  (:documentation "Nucleotide sequences can be retrieved from genomic
  +databases (like Ensembl) which is implemented in CBCL. From Ensembl,
  +nucleotides can also be retrieved as genes (with exons and introns) or
  +transcripts. Specialised databases offer information on expressed
  +sequence tags (ESTs)."))
   
   (defclass amino-acid-sequence (bio-sequence) ()
     (:documentation "A real protein or at least some smallish peptide."))
  
positive.code: 
  
  (defun orthogonal-coded (char)
    "Albert, please describe."
    (declare (type character char))
    (flet ((char-eq (c)
             (char-equal char c)))
  
negative.code: (defclass feature ()
    ((feature-type :accessor feature-type
                   :initarg :feature-type))
    (:documentation "A property of interest that is referred to from a
  biological entity, i.e, a biological sequence."))
  
  (defgeneric shuffle-sequence (seq)
    (:documentation "Return a randomly shuffled copy of the sequence." )
  