<spanclass="n">PADDLE_ENFORCE</span><spanclass="p">(</span><spanclass="n">symbols_ready_</span><spanclass="p">,</span><spanclass="s">"operators and variables should be created first."</span><spanclass="p">);</span>
<spanclass="n">PADDLE_ENFORCE</span><spanclass="p">(</span><spanclass="n">symbols_ready_</span><spanclass="p">,</span><spanclass="s">"operators and variables should be created first."</span><spanclass="p">);</span>