title: Plotting expression trees in R
body: <p>I know that I can create an expression tree in R using the <code>substitute</code> function. Let's say that I generate the following expression tree:</p>
  
  <pre><code>expT &lt;- substitute(a+(2*b+c))
  </code></pre>
  
  <p>Is it possible to visualize the expression tree in R, producing something like:</p>
  
  <p><img src="https://i.imgur.com/SEfAOLS.jpg" alt="Expression Tree"></p>
  
  <p>I know that <code>(</code> is also a function in R, but I would like to omit that in the plot.</p>