text: _base_ = [
      '../_base_/models/faster_rcnn_r50_fpn.py',
      '../_base_/datasets/coco_detection.py',
      '../_base_/schedules/schedule_1x.py', '../_base_/default_runtime.py'
  ]
  norm_cfg = dict(type='GN', num_groups=32, requires_grad=True)
  model = dict(
      pretrained=None,
      backbone=dict(
          frozen_stages=-1, zero_init_residual=False, norm_cfg=norm_cfg),
      neck=dict(norm_cfg=norm_cfg),
      roi_head=dict(
          bbox_head=dict(
              type='Shared4Conv1FCBBoxHead',
              conv_out_channels=256,
              norm_cfg=norm_cfg)))
  # optimizer
  optimizer = dict(paramwise_cfg=dict(norm_decay_mult=0))
  optimizer_config = dict(_delete_=True, grad_clip=None)
  # learning policy
  lr_config = dict(warmup_ratio=0.1, step=[65, 71])
  runner = dict(type='EpochBasedRunner', max_epochs=73)
  