code: def get_layout(layout: Optional[str] = None) -> str:
      if layout is None:
          layout = "coo"
          warnings.warn(
              "`layout` argument unset, using default layout "
              '"coo". This may lead to unexpected behaviour.'
          )
      assert layout == "coo" or layout == "csr" or layout == "csc"
      return layout
  
imports: import warnings
  from typing import List, Optional, Tuple
  import torch
  from torch_scatter import scatter_add, segment_csr
  from torch_sparse.utils import Final, index_sort
label_desc: Use image node_id 1 for calling a global function with example usage: get_layout(layout) and returns: layout