title: nested loops, return list that contain only even integers
body: <pre><code>def only_evens(lst):
      """ (list of list of int) -&gt; list of list of int
  
      Return a list of the lists in lst that contain only even integers. 
  
      &gt;&gt;&gt; only_evens([[1, 2, 4], [4, 0, 6], [22, 4, 3], [2]])
      [[4, 0, 6], [2]]
      """
  
      even_lists = []
  
      for sublist in lst:
  
          even_lists = []
  
      for sublist in lst:
  
          for numb in sublist:
              if numb[i]%2 == 0:
                  even_list.append(sublist)
  
      return even_lists
  </code></pre>
  
  <p>I got this error: NameError: global name 'i' is not defined
  and what is wrong with the body of function?</p>