Where is torch.ops.torch_sparse.spmm_sum?

[mdanb]

I'm trying to better understand how aggregation works for SparseTensors. I'm looking at the spmm_sum function from torch-sparse in matmul.py:

def spmm_sum(src: SparseTensor, other: torch.Tensor) -> torch.Tensor:
    rowptr, col, value = src.csr()

    row = src.storage._row
    csr2csc = src.storage._csr2csc
    colptr = src.storage._colptr

    if value is not None and value.requires_grad:
        row = src.storage.row()

    if other.requires_grad:
        row = src.storage.row()
        csr2csc = src.storage.csr2csc()
        colptr = src.storage.colptr()

    return torch.ops.torch_sparse.spmm_sum(row, rowptr, col, value, colptr,
                                           csr2csc, other)

I can't seem to find
torch.ops.torch_sparse.spmm_sum(row, rowptr, col, value, colptr, csr2csc, other)
How can I access this function?

[mdanb]

Answered here