title: JQuery Add / Subtract value from input inside the li where the button was clicked
body: <p>I have a unordered list.
  Each has 2 buttons and one input.
  One button would add the current value of the input and the other would subtract.</p>
  
  <p>As there would be more that 1 <LI></p>
  
  <p>Here's the html:</p>
  
  <pre><code>&lt;ul&gt;
      &lt;li&gt;
          &lt;button class="add"&gt;Add&lt;/button&gt;
          &lt;input type="text" value="0" /&gt;
          &lt;button class="subtract"&gt;Subtract&lt;/button&gt;
      &lt;/li&gt;
  
      &lt;li&gt;
          &lt;button class="add"&gt;Add&lt;/button&gt;
          &lt;input type="text" value="0" /&gt;
          &lt;button class="subtract"&gt;Subtract&lt;/button&gt;
      &lt;/li&gt;
  
  &lt;/ul&gt;
  </code></pre>
  
  <p>How could I use JQuery for each <LI> values to be independent?</p>