code: function (puzzle) {
                  var puzzleString = '';
                  for (var i = 0, height = puzzle.length; i < height; i++) {
                      var row = puzzle[i];
                      for (var j = 0, width = row.length; j < width; j++) {
                          puzzleString += (row[j] === '' ? ' ' : row[j]) + ' ';
                      }
                      puzzleString += '\n';
                  }
                  console.log(puzzleString);
                  return puzzleString;
              }
docs: Outputs a puzzle to the console, useful for debugging.
  Returns a formatted string representing the puzzle.
  
  @param {[[String]]} puzzle: The current state of the puzzle
  @api public