text: export function SudokuBoardDirective() {
      'ngInject';
  
      let directive = {
          restrict: 'E',
          templateUrl: 'app/components/sudoku-board/sudoku-board.html',
          scope: {
              board: '='
          },
          controller: SudokuBoardController,
          controllerAs: 'vm',
          bindToController: true
      };
  
      return directive;
  }
  
  class SudokuBoardController {
      constructor($log) {
          'ngInject';
          this.log = $log;
      }
  
      increaseValue(column) {
          if (column.value === 9) {
              column.value = 0;
          } else {
              column.value++;
          }
      }
  
  }