# in the same file and package as before

sub calculate_aggr_infos_with_readers {
    my $hash_data_reader_of_file = shift;

    my @data_files = keys %{$hash_data_reader_of_file};

    DATA:
    while ( $hash_data_now = get_next_data_for_all_readers($hash_data_reader_of_file) ) {

        # check that the time value is the same for each set of data
        check_if_time_is_the_same_for_all_data($hash_data_reader_of_file);

        # calculate aggregated information
        my $hash_aggr_infos = calculate_aggr_infos_from_data($hash_data_now);
        
        # it’s a bit more complex, as i need a bit of “past data history” 
        # to calculate the aggregated information

    } # end while (DATA)    

} # - - - end sub calculate_aggr_infos_with_readers()