   'spacer',
                'spacer',
                'pageLength',
                'spacer',
                {
                  extend: 'collection',
                  text: 'More',
                  buttons: [
                    {
                      extend: 'colvis',
                      text: 'Visible columns',
                      columns: [1,2,3,4,5,6],
                    },
                    // {
                    //   extend: 'csv',
                    //   exportOptions: {
             