anchor.diff:  ;;; ----------------
   (defgeneric protein-features-of-type (protein feat-type)
     (:documentation "Get all protein-features of a certain type for the
  -given protein. If type is nil, all features of the protein are returned")
  +given protein. If type is nil, all features of the protein are returned
  +
  +Example:
  +
  +* (defparameter *ts* (car (transcripts (sample-gene-rhodopsin))))
  +* (defparameter *tl* (translation *ts*))
  +* (protein-features-of-type *tl* \"transmembrane\")
  +
  +(#<PROTEIN-FEATURE {BA8E7E9}> #<PROTEIN-FEATURE {BA8F051}>
  +  #<PROTEIN-FEATURE {BA8F8B9}> #<PROTEIN-FEATURE {BA90129}>
  +   #<PROTEIN-FEATURE {BA90991}> #<PROTEIN-FEATURE {BA911F9}>
  +    #<PROTEIN-FEATURE {BA91A61}>)
  +
  +")
   
     (:method ((transl translation) (type (eql nil)))
       (declare (ignore type))
  
positive.code:       ;; FIXME:check if we have the name of the chromosome or
        ;; something else.
      chr-name))
  (defgeneric coordinate-system (ens-obj)
    (:documentation "Return the coordinate system of the object."))
  (defmethod coordinate-system ((ens-obj dna-sequence))
  
negative.code:   "The length of the sequence on the genome.
  
  ###Example:
  * (seq-length (sample-gene-rhodopsin))
  
  6695
  * (seq-length (sample-gene-tp53))
  
  19197"
    (with-slots ((seq-start seq-region-start)
                 (seq-end   seq-region-end))
        ens-obj
  