Generate a sharded filename. The filename is printf formatted as
  }];

  let description = [{
%s-%05d-of-%05d, basename, shard, num_shards.
  }];

  let arguments = (ins
    TF_StrTensor:$basename,
    TF_Int32Tensor:$shard,
    TF_Int32Tensor:$num_shards
  );

  let results = (outs
    TF_StrTensor:$filename
  );
}