Function encode_for_uri 

pub fn encode_for_uri<N: DomNavigator>(
    _context: &mut DynamicContext<'_, N>,
    args: Vec<XPathValue<N>>,
) -> Result<XPathValue<N>, XPathError>

fn:encode-for-uri($uri-part as xs:string?) as xs:string

Encodes a string for use in a URI.