code: def group_std(
      x, groups: int = 32, eps: float = 1e-5, flatten: bool = False
  ):
      B, C, H, W = x.shape
      x_dtype = x.dtype
      _assert(C % groups == 0, "")
      if flatten:
          x = x.reshape(
              B, groups, -1
          )  # FIXME simpler shape causing TPU / XLA issues
          std = (
              x.float()
              .var(dim=2, unbiased=False, keepdim=True)
              .add(eps)
              .sqrt()
              .to(x_dtype)
          )
      else:
          x = x.reshape(B, groups, C // groups, H, W)
          std = (
              x.float()
              .var(dim=(2, 3, 4), unbiased=False, keepdim=True)
              .add(eps)
              .sqrt()
              .to(x_dtype)
          )
      return std.expand(x.shape).reshape(B, C, H, W)
  
imports: from typing import Sequence, Union
  import torch
  import torch.nn
  import torch.nn.functional
  from .create_act import create_act_layer
  from .trace_utils import _assert
label_desc: Use image node_id 5 for calling a global function with example usage: group_std(x, groups, eps, flatten) and returns: std