+`content` and should return the filtered content.
+
+### sanitize
+
+ IkiWiki::hook(type => "filter", id => "foo", call => \&sanitize);
+
+Use this to implement html sanitization or anything else that needs to
+modify the content of a page after it has been fully converted to html.
+The function is passed the page content and should return the sanitized
+content.