title: Find index of element in a list using recursion
body: <pre><code>def index(L,v)
      ''' Return index of value v in L '''
      pass
  </code></pre>
  
  <p>I need help with implementing this function using recursion.
  Really new to recursion stuff so any advice would help!</p>
  
  <p>Note that <code>L</code> is a list. <code>v</code> is a value.</p>