title: collections.deque get index of element by value
body: <p>For list we can get index of element <code>list_name.index(3)</code></p>
  
  <p>How to get index of item in deque.</p>
  
  <p>ex:
  <code>d_list = deque([1, 2, 3, 4])</code> what is the best way to get the index of element 3.</p>
  
  <p>Edit:
  I am using Python 2.7.6</p>