ExtFunctions = {('http://exslt.org/sets', 'difference'): <function Difference>, ('http://exslt.org/sets', 'distinct'): <function Distinct>, ('http://exslt.org/sets', 'has-same-node'): <function HasSameNode>, ('http://exslt.org/sets', 'intersection'): <function Intersection>, ('http://exslt.org/sets', 'leading'): <function Leading>, ('http://exslt.org/sets', 'trailing'): <function Trailing>}