sub write_vars {
    my $filename = shift(@_);
    my $vars = shift(@_);
   
    open(FILE, ">$filename");
    
    foreach my $key (keys %{$vars}) {
	my $i = \( $vars->{$key} );
        # this is a switch statement
        # make a reference to $vars->{$key} and pass it to ref
        for ( ref $i ) {
            if (/SCALAR/) {
                print $key . " = " . $vars->{$key} . "\n";
            }
            else {
		$j = $vars->{$key};
                $type = ref $j;
		print $type . "\n";
                if ($type eq "ARRAY") {
                    for my $k ( @{$j} ) {
                        print $k . "\n";
                    }
                }
                elsif ($type eq "HASH") {
		    for my $l ( keys %{$j} ) {
			print $l . ": " . $j->{$l} . "\n";
		    }
                }
            }
        }
    }
   
    close(FILE);
        
    return;
}

%a = qw(One 1 Three 3);
%foo = ('a', \%a, 'b', 'B', 'c', 'C');

write_vars("test.txt", \%foo);