fn.baseUrifn.baseurifnbaseuri/apidoc/8.0/fn:base-uri.xml
Returns the value of the base-uri property for the specified node. If the
node is part of a document and does not have a base-uri attribute explicitly
set, fn:base-uri typically returns the URI of the document
in which the node resides.
The node whose base-uri is to be returned.
argNode?String?
var x = cts.doc("/bar.json");
fn.baseUri(x);
=> "/bar.json"