title: How to export the output of gplearn as a sympy expression or some other readable format?
body: <p>As much as this may sound like a simple task, I have not encountered a way to do it though the documentation.</p>
  
  <p>After running an arbitrary routine (such as one of these <a href="http://gplearn.readthedocs.io/en/stable/examples.html#example" rel="noreferrer">examples</a>, I get something like</p>
  
  <pre><code>&gt;&gt;&gt; print(est_gp)
  sqrt(div(add(1.000, sub(div(sqrt(log(0.978)), X0), mul(-0.993, X0))),add(-0.583, 0.592)))
  </code></pre>
  
  <p>How do I (or can I even) convert this to an expression that can be used outside <code>gplearn</code>, like a <code>sympy</code> expression?</p>