title: PyParsing: What does Combine() do?
body: <p>What is the difference between:</p>
  
  <pre><code>foo = TOKEN1 + TOKEN2
  </code></pre>
  
  <p>and</p>
  
  <pre><code>foo = Combine(TOKEN1 + TOKEN2)
  </code></pre>
  
  <p>Thanks. </p>
  
  <p><strong>UPDATE</strong>: Based on my experimentation, it seems like <code>Combine()</code> is for terminals, where you're trying to build an expression to match on, whereas plain <code>+</code> is for non-terminals. But I'm not sure.</p>