code: public synchronized Sandbox sandbox() {
          if (null != _secureExecutor) {
              return new Sandbox(this, _secureExecutor);
          }
          int poolSize = (Integer) conf().get(RythmConfigurationKey.SANDBOX_POOL_SIZE);
          SecurityManager csm = conf().get(RythmConfigurationKey.SANDBOX_SECURITY_MANAGER_IMPL);
          int timeout = (Integer) conf().get(RythmConfigurationKey.SANDBOX_TIMEOUT);
          SandboxThreadFactory fact = conf().get(RythmConfigurationKey.SANBOX_THREAD_FACTORY_IMPL);
  
          SecurityManager ssm = System.getSecurityManager();
          RythmSecurityManager rsm;
          String code;
          if (null == ssm || !(ssm instanceof RythmSecurityManager)) {
              code = conf().get(RythmConfigurationKey.SANDBOX_SECURE_CODE);
              rsm = new RythmSecurityManager(csm, code, this);
          } else {
              rsm = ((RythmSecurityManager) ssm);
              code = rsm.getCode();
          }
          secureCode = code;
          _secureExecutor = new SandboxExecutingService(poolSize, fact, timeout, this, code);
          Sandbox sandbox = new Sandbox(this, _secureExecutor);
          if (ssm != rsm) System.setSecurityManager(rsm);
          return sandbox;
      }
docs: Create a {@link Sandbox} instance to render the template
  
  @return an new sandbox instance