The function is passed named parameters "page" and "content". Its return
value is ignored.
-### rescan
-
- hook(type => "rescan", id => "foo", call => \&scan);
-
-This hook is called after the scan hook has been run, as well as the
-preprocess hook in scan mode. It is used to collect additional
-metadata that depends on a first scan to have been performed already.
-
-The function is passed named parameters "page" and "content". Its return
-value is ignored.
-
### filter
hook(type => "filter", id => "foo", call => \&filter);