How to clojail a symbol

project.clj

(defproject test-cljail "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.8.0"]
                 [clojail "1.0.6"]])

repl.clj

(ns my.project
  (:use [clojail.core :only [sandbox]]
        [clojail.testers :only [blacklist-symbols blacklist-objects]]))


(def tester [(blacklist-symbols #{'alter-var-root 'clojure.string/blank?})
             (blacklist-objects [java.lang.Thread])]) ; Create a blacklist.

(def sb (sandbox tester :timeout 5000))

(sb '(println (clojure.string/blank? "")))