Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
format => 'ISBN-10',
strip_hyphens => 1,
}
- );
+ ) if $isbn;
}
=head2 NormalizedISBN
my $strip_hyphens = $params->{strip_hyphens};
my $format = $params->{format};
+ return unless $string;
+
my $isbn = Business::ISBN->new($string);
if ( $isbn && $isbn->error != Business::ISBN::BAD_ISBN ) {
sub GetVariationsOfISBN {
my ($isbn) = @_;
+ return unless $isbn;
+
my @isbns;
push( @isbns, NormalizeISBN({ isbn => $isbn }) );