def METHOD_NAME (self, session) :
    # make sure we have can access the proxy
    api = self.get_api ()
    if  not api.user_proxy :
        api.user_proxy = "x509up_u%d"  %  os.getuid()
    if  not os.path.exists (api.user_proxy) or \
        not os.path.isfile (api.user_proxy)    :
        raise BadParameter ("X509 proxy does not exist: %s" % api.user_proxy)
    try :
        fh = open (api.user_proxy)
    except Exception as e:
        raise PermissionDenied ("X509 proxy '%s' not readable: %s" \
                             % (api.user_proxy, str(e))) from e
    else :
        fh.close ()