anchor.diff:    "Create a fresh-instance of `component-class` and add it to the components of 
      `entity`.
      `component-initargs` are supplied to `(make-instance component-class …)`."
  -  (with-existing-entity2 entity
  +  (with-existing-entity* entity
       (apply #'make-instance (append (list component-class :entity entity) component-initargs))))
   
   
  
positive.code:     (f)))
  
  
  (defmacro with-existing-entity2 (entity &body body)
    `(with-existing-entity ,entity (lambda (entity) ,@body)))
  
  
  
negative.code:   "Return all `Components` of `entity`.
     If `component-type` is specified, only the `Components` of `component-type`
     are returned otherwise all `Components` are returned."
    (with-existing-entity* entity
      (remove-if-not (lambda (x) (eql x entity)) 
                       (get-components-of-type component-type) 
                       :key #'entity)))
  