groups

[{
    column_id: 'first_grouped_column',
    groups: [{
        count: 12,
        value: 'A'
    }, {
        count: 14,
        value: 'B'
    }]
 }, {
    column_id: 'second_grouped_column',
    groups: [{
        count: 12,
        value: '1',
        parent: ['A']
      }, {
        count: 14,
        value: '1',
        parent: ['B']
      }]
 }, , {
    column_id: 'third_grouped_column',
    groups: [{
        count: 12,
        value: '1',
        parent: ['A', '1']
      }, {
        count: 14,
        value: '1',
        parent: ['B', '1']
      }]
 }]