sub ReadSource{
    my ($DataSource, $HashRef) = @_;
    my @Data = get_data();
    for (@Data){
      my $item = $HashRef->{$_} ||= [];
      push( @$item, $DataSource );
    }
}


##</code><code>##

sub ReadSource{
    my ($DataSource, $HashRef) = @_;
    my @Data = get_data();
    push( @{ $HashRef->{$_} ||= [] }, $DataSource )
     for @Data;
}