title: Check if all strings in one array are in another array
body: <p>This is for a tic tac toe game. I have an array <code>board</code> with nine string elements, and a nested array <code>WIN_COMBINATIONS</code> with position combinations from <code>board</code>:</p>
  
  <pre><code>board = ["X", "X", "X", " ", " ", " ", " ", " ", " "]
  
  WIN_COMBINATIONS = [
    [0, 1, 2],
    [0, 3, 6],
    [0, 4, 8],
    [3, 4, 5],
    [6, 7, 8],
    [6, 4, 2],
    [1, 4, 7],
    [2, 5, 8]
  ]
  </code></pre>
  
  <p>How do I choose the array combinations from <code>board</code> that are all <code>"X"</code> or all <code>"O"</code> using the combinations found in <code>WIN_COMBINATIONS</code>?</p>
  
  <p>For example
       a different board than the one above in which X wins in the right diagonal.</p>
  
  <pre><code>board = ["X", "O", "X", "O", "X", "O", "X", "X", "O"]
  
  #  X | O | X
  # ---+---+---
  #  O | X | O
  # ---+---+---
  #  X | X | O
  
  won?(board) #=&gt; [2,4,6]
  </code></pre>