sub Main {
    my $workbook;
    my $name;
    my $Graph_table_last_row;
    my $row;
    my $var1;
    my $var2;
    my $grpsheet;
    my $graph_table_no;

    ...
    
    ($Graph_table_last_row, $graph_table_no) =
        add_chart_func ($workbook, $name, $Graph_table_last_row, $row, $var1,
        $var2, $grpsheet, $graph_table_no);
        
    ...
}


sub add_chart_func {
    my ($workbook, $name, $Graph_table_last_row, $row, $var1, $var2, $grpsheet,
        $graph_table_no)
        = @_;

    ...;

    $Graph_table_last_row = $row + 5;
    $graph_table_no++;

    return $Graph_table_last_row, $graph_table_no;
}