Man pages matching name www::mechanize::treebuilder in section 3pm:

WWW::Mechanize::TreeBuilder.3pm.en	debian 10 / libwww-mechanize-treebuilder-perl
WWW::Mechanize::TreeBuilder.3pm.en	debian 11 / libwww-mechanize-treebuilder-perl
WWW::Mechanize::TreeBuilder.3pm.en	debian 12 / libwww-mechanize-treebuilder-perl