anchor.diff:        (setf (frames file)
               (parse-frames
                (cl-ppcre:split "[\\r\\n]+" data)
  -             markers))
  +             markers
  +             file))
         file)))
  
positive.code:   (:method ((metric (eql :m)) field)
      (parse-field-for-metric :float field)))
  
  (defun parse-frame (data markers)
    (let ((frame (make-instance 'frame :id (parse-integer (first data))
                                       :sub-id (parse-integer (second data))))
          (data (cddr data)))
      (loop for (marker . fields) in markers
            for point = (make-instance 'marker-point :marker marker)
  
negative.code:             (pathname-name (file file)))))
  
  (defclass frame ()
    ((vicon-file :initarg :vicon-file :accessor vicon-file)
     (id :initarg :id :accessor id)
     (sub-id :initarg :sub-id :accessor sub-id)
     (points :initarg :points :accessor points))
    (:default-initargs
     :vicon-file (error "VICON-FILE required.")
     :id (error "ID required.")
     :sub-id NIL
     :points (make-hash-table :test 'eql)))
  