text: app.controller('Ctrl6a', function($scope) {
      $scope.users = [
          {id: 1, name: 'Aaron'},
          {id: 2, name: 'David'},
          {id: 2, name: 'Moses'}
      ];
  
      $scope.selectedUsers = [];
  
      $scope.checkFirst = function() {
          $scope.selectedUsers.splice(0, $scope.selectedUsers.length, $scope.users[0]);
      };
  
      $scope.checkAll = function() {
          $scope.selectedUsers.splice(0, $scope.selectedUsers.length);
          for (var i in $scope.users) {
               $scope.selectedUsers.push($scope.users[i]);
          }
      };
  
      $scope.uncheckAll = function() {
          $scope.selectedUsers.splice(0, $scope.selectedUsers.length);
      }
  });