old_contents: from django.utils.translation import ugettext_lazy as _
  
  from rest_framework import serializers
  
  from . import models
  
  
  class UserStoryExistsValidator:
      def validate_us_id(self, attrs, source):
          value = attrs[source]
          if not models.UserStory.objects.filter(pk=value).exists():
              msg = _("There's no user story with that id")
              raise serializers.ValidationError(msg)
          return attrs
  
new_contents: # Copyright (C) 2015 Andrey Antukh <niwi@niwi.be>
  # Copyright (C) 2015 Jesús Espino <jespinog@gmail.com>
  # Copyright (C) 2015 David Barragán <bameda@dbarragan.com>
  # This program is free software: you can redistribute it and/or modify
  # it under the terms of the GNU Affero General Public License as
  # published by the Free Software Foundation, either version 3 of the
  # License, or (at your option) any later version.
  #
  # This program is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU Affero General Public License for more details.
  #
  # You should have received a copy of the GNU Affero General Public License
  # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  
  from django.utils.translation import ugettext_lazy as _
  
  from rest_framework import serializers
  
  from . import models
  
  
  class UserStoryExistsValidator:
      def validate_us_id(self, attrs, source):
          value = attrs[source]
          if not models.UserStory.objects.filter(pk=value).exists():
              msg = _("There's no user story with that id")
              raise serializers.ValidationError(msg)
          return attrs
  
subject: Add license