title: Nested List and count()
body: <p>I want to get the number of times x appears in the nested list.</p>
  
  <p>if the list is:</p>
  
  <pre><code>list = [1, 2, 1, 1, 4]
  list.count(1)
  &gt;&gt;3
  </code></pre>
  
  <p>This is OK. But if the list is:</p>
  
  <pre><code>list = [[1, 2, 3],[1, 1, 1]]
  </code></pre>
  
  <p>How can I get the number of times 1 appears? In this case, 4.</p>