code: def rowptr(self) -> torch.Tensor:
      rowptr = self._rowptr
      if rowptr is not None:
          return rowptr
  
      row = self._row
      if row is not None:
          rowptr = torch.ops.torch_sparse.ind2ptr(
              row, self._sparse_sizes[0]
          )
          self._rowptr = rowptr
          return rowptr
  
      raise ValueError
  
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 6 for calling the SparseStorage obj's underlying member method code with example usage: obj.rowptr() and returns: rowptr, rowptr