'Respond to a request for all Neutron API versions.'

@webob.dec.wsgify(RequestClass=wsgi.Request)
def __call__(self, req):

    version_objs = [{'id': 'v2.0', 'status': 'CURRENT'}]
    if (req.path != '/'):
        if self.app:
            return req.get_response(self.app)
        language = req.best_match_language()
        msg = _('Unknown    API    version    specified')
        msg = oslo_i18n.translate(msg, language)
        return webob.exc.HTTPNotFound(explanation=msg)
    builder = versions_view.get_view_builder(req)
    versions = [builder.build(version) for version in version_objs]
    response = dict(versions=versions)
    metadata = {}
    content_type = req.best_match_content_type()
    body = wsgi.Serializer(metadata=metadata).serialize(response, content_type)
    response = webob.Response()
    response.content_type = content_type
    response.body = wsgi.encode_body(body)
    return response
