and undef if a rebuild could be needed in some circumstances, but is not
strictly required.
+### genwrapper
+
+ hook(type => "genwrapper", id => "foo", call => \&genwrapper);
+
+This hook is used to inject C code (which it returns) into the `main`
+function of the ikiwiki wrapper when it is being generated.
+
## Plugin interface
To import the ikiwiki plugin interface: