title: Antlr4: Generating a Lisp s-expression style output from an expression
body: <p>Referring to this <a href="https://theantlrguy.atlassian.net/wiki/display/ANTLR3/Tree+construction" rel="nofollow">link</a>. It shows how to create a lisp style s-expression
  from any infix expression on Antlr3.</p>
  
  <p>I am using Antlr4 and it doesn't seem to work on it.</p>
  
  <p>Can someone please suggest me some way to achieve it ?</p>
  
  <p><code>2x+3x^5</code> to <code>(+ (* 2 x) (* 3 (^ x 5)))</code> </p>