title: How to match integers in NLTK CFG?
body: <p>If I want to define a grammar in which one of the tokens will match an integer, how can i achieve it using nltk's string CFG?</p>
  
  <p>For example -</p>
  
  <pre><code>S -&gt; SK SO FK
  SK -&gt; 'SELECT'
  SO -&gt; '\d+'
  FK -&gt; 'FROM'
  </code></pre>