code: def _assert_strides_are_log2_contiguous(strides):
      """
      Assert that each stride is 2x times its preceding stride, i.e. "contiguous in log2".
      """
      for i, stride in enumerate(strides[1:], 1):
          assert (
              stride == 2 * strides[i - 1]
          ), "Strides {} {} are not log2 contiguous".format(
              stride, strides[i - 1]
          )
  
imports: import math
  import fvcore.nn.weight_init
  import torch
  import torch.nn.functional
  from torch import nn
  from detectron2.layers import Conv2d, ShapeSpec, get_norm
  from .backbone import Backbone
  from .build import BACKBONE_REGISTRY
  from .resnet import build_resnet_backbone
label_desc: Use image node_id 1 for calling a global function with example usage: _assert_strides_are_log2_contiguous(strides) without return types