my @row_indices    = $row1 .. $rowN;
my @column_indices = $col1 .. $colN;
my @row_subset;
for my $row_idx (@row_indices) {
	my $row = $$data[$row_idx];     # deref $data and get row
	my $column_subset_aliases =
		sub{ \@_ }->(
			@$row[@column_indices]  # deref $row and get array slice
		);
	push @row_subset, $column_subset_aliases;
}
return \@row_subset;