title: Splitting list by keyword
body: <p>I have a list as follows:</p>
  
  <pre><code>['MARK_A', 8, 7702.5, 13, 7703, 983472],
  ['MARK_B', 10, 7702.5, 983472],
  ['MARK_B', 3, 7703.5, 983472],
  ['MARK_B', 6, 7701.2, 983472],
  ['MARK_B', 5, 7704.4, 983472],
  ['MARK_A', 9, 7701.5, 11, 7704, 983475],
  ['MARK_B', 10, 7702.5, 983475],
  ['MARK_B', 3, 7703.5, 983475],
  ['MARK_B', 6, 7701.2, 983475],
  ['MARK_B', 5, 7704.4, 983475]]
  </code></pre>
  
  <p>How is it possible to split this list into 2 lists like as follows:</p>
  
  <pre><code>[['MARK_A', 8, 7702.5, 13, 7703, 983472],
  ['MARK_B', 10, 7702.5, 983472],
  ['MARK_B', 3, 7703.5, 983472],
  ['MARK_B', 6, 7701.2, 983472],
  ['MARK_B', 5, 7704.4, 983472]],
  [ ['MARK_A', 9, 7701.5, 11, 7704, 983475],
  ['MARK_B', 10, 7702.5, 983475],
  ['MARK_B', 3, 7703.5, 983475],
  ['MARK_B', 6, 7701.2, 983475],
  ['MARK_B', 5, 7704.4, 983475]]
  </code></pre>
  
  <p>There can be any number of "MARK_A" in list followed by one or more "MARK_B". I would be dividing the lists by the [-1] element</p>