Content of buffer4.xq example
import module namespace geo = "http://expath.org/ns/geo";
declare namespace gml="http://www.opengis.net/gml";
geo:buffer(<gml:LinearRing>
<gml:posList>
1 1
20 1
50 30
1 1
</gml:posList>
</gml:LinearRing>,
1
)