Koha::SearchEngine::Search - instantiate the search object that corresponds to the SearchEngine system preference.
This allows you to be agnostic about what the search engine configuration is and just get whatever search object you need.
use Koha::SearchEngine::Search;
my $searcher = Koha::SearchEngine::Search->new();
Creates a new Search of whatever the relevant type is.
my $biblionumber = $searcher->extract_biblionumber( $marc );
Returns the biblionumber from $marc. The routine is called from the extract_biblionumber method of the specific search engine.