title: Python removing elements from a 2d array depending on first item
body: <p>If I were to have a 2d array in python, say</p>
  
  <pre><code>lst = [['a','1', '2'], ['b', 1, 2], ['c', 1, 2], ['b', 3, 4]]
  </code></pre>
  
  <p>I'd like a way to remove any items from lst where the first item is 'b', so that you return with:</p>
  
  <pre><code>[['a','1', '2'], ['c', 1, 2]]
  </code></pre>
  
  <p>Any help would be greatly appreciated, preferred if only built in libraries are used. Thanks</p>