anchor.diff:    (:documentation "Generates a Ohm Model Class Key.")
     (:method :before ((model ohm-model) &rest segments)
              (declare (ignore segments))
  -           (unless (managed-object-p model)
  -             (error 'ohm-missig-id-error :object model)))
  +           (ensure-managed-object model))
     (:method ((model ohm-model) &rest segments)
       (apply #'make-key (class-name (class-of model)) segments)))
   
  
positive.code:    (savedp :reader savedp)))
  
  (defmacro defohm (name superclasses slots)
    `(defclass ,name ,(cons 'ohm-model superclasses)
       ,slots
       (:metaclass ohm-metaclass)))
  
  (defgeneric managed-object-p (model)
    (:documentation "Tests if the given MODEL has been persisted resp. is dirty or not.")
    (:method ((model ohm-model))
      (slot-boundp model 'id)))
  
  (defun make-key (&rest segments)
    (with-output-to-string (out)
      (format out "~{~A~^:~}" segments)))
  
  (defgeneric object-key (model &rest segments)
    (:documentation "Generates an Ohm model object key.")
    (:method :before ((model ohm-model) &rest segments)
             (declare (ignore segments))
             (unless (managed-object-p model)
               (error 'ohm-missig-id-error :object model)))
    (:method ((model ohm-model) &rest segments)
      (apply #'make-key (class-name (class-of model)) (id model) segments)))
  
  
negative.code:      nconc (list (make-keyword key) value)))
  
  (defun object->plist (object)
    "Takes an OBJECT and represents it a plist.
  This function returns two lists. A object attributes plist and
  a second list with index keys."
    (loop with index-keys = nil
       for slot in (closer-mop:class-slots (class-of object))
       for slot-name = (closer-mop:slot-definition-name slot)
       when (slot-boundp object slot-name)
       unless (ohm-model-slot-p slot-name)
       nconc (let ((slot-value (slot-value object slot-name)))
               (when (indexp slot)
                 (push (class-key object 'indices slot-name slot-value) index-keys))
  