register-function expression perl-code
EXPERIMENTAL!
Registers a given perl code as a new XPath extension function under a name provided in the first argument. XML::LibXML DOM API as well as all Perl functions pre-defined in the XML::XSH2::Map namespace may be used in the perl code for object processing. If the name contains a colon, then the first part before the colon must be a registered namespace prefix (see register-namespace) and the function is registered within the corresponding namespace.