code: def get_comment_ids_by_books(self, book_ids):
          
          # Implemented from template for
          # osid.resource.ResourceBinSession.get_resource_ids_by_bins
          id_list = []
          for comment in self.get_comments_by_books(book_ids):
              id_list.append(comment.get_id())
          return IdList(id_list)
docs: Gets the list of ``Comment Ids`` corresponding to a list of ``Book`` objects.
  
          arg:    book_ids (osid.id.IdList): list of book ``Ids``
          return: (osid.id.IdList) - list of comment ``Ids``
          raise:  NullArgument - ``book_ids`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*