text: _base_ = './retinanet_r50_fpn_1x_coco.py'
  model = dict(
      pretrained='open-mmlab://resnext101_32x4d',
      backbone=dict(
          type='ResNeXt',
          depth=101,
          groups=32,
          base_width=4,
          num_stages=4,
          out_indices=(0, 1, 2, 3),
          frozen_stages=1,
          norm_cfg=dict(type='BN', requires_grad=True),
          style='pytorch'))
  