title: attempt to index field ? (nil value)
body: <p>I am not sure where the problem is. Anyone know why?</p>
  
  <pre><code>function check(board, color, row, col)
  --if same color, change tile to "o"
  
  if board[row][col] == color then -- attempt to index nil?
      board[row][col] = "o"
      count = count + 1
      return "o"
  end
  
  return
  </code></pre>
  
  <p>end</p>