code: def test_batch_norm_single_element():
      x = torch.randn(1, 16)
  
      norm = BatchNorm(16)
      with pytest.raises(
          ValueError, match="Expected more than 1 value"
      ):
          norm(x)
  
      with pytest.raises(
          ValueError, match="requires 'track_running_stats'"
      ):
          norm = BatchNorm(
              16, track_running_stats=False, allow_single_element=True
          )
  
      norm = BatchNorm(
          16, track_running_stats=True, allow_single_element=True
      )
      out = norm(x)
      assert torch.allclose(out, x)
  
imports: import pytest
  import torch
  from torch_geometric.nn import BatchNorm, HeteroBatchNorm
  from torch_geometric.testing import is_full_test, withCUDA
label_desc: Use image node_id 2 for calling a global function with example usage: test_batch_norm_single_element() without return types