title: Rails and forms: drop down with range of numbers and Unlimited
body: <p>I have this right now:</p>
  
  <pre><code>&lt;%= f.select :credit, (0..500) %&gt;
  </code></pre>
  
  <p>This will result in this:</p>
  
  <pre><code>&lt;option value="1"&gt;1&lt;/option&gt;
  &lt;option value="2"&gt;2&lt;/option&gt;
  &lt;option value="3"&gt;3&lt;/option&gt;
  &lt;option value="4"&gt;4&lt;/option&gt;
  &lt;option value="5"&gt;5&lt;/option&gt;
  &lt;option value="6"&gt;6&lt;/option&gt;
  &lt;option value="7"&gt;7&lt;/option&gt;
  &lt;option value="8"&gt;8&lt;/option&gt;
  &lt;option value="9"&gt;9&lt;/option&gt;
  ...
  </code></pre>
  
  <p>How would I add another option in that select that would be "<strong>All</strong>" and which value should be <strong>nil</strong>?</p>