         return xmlXPathCastToBoolean(ptr) != 0
     }
 
+    // TODO: Use "Double" instead of "Number" on the Swift side?
     public func asNumber() -> Double {
         return xmlXPathCastToNumber(ptr)
     }

        xmlXPathFreeCompExpr(ptr);
    }

    public func evaluateOn(node: Node) throws -> XPathResult {
        let context = try XPathContext(node: node)
        let obj = xmlXPathCompiledEval(ptr, context.ptr)

    }

    public func asNodeSet() -> [Node]? {
        // TODO: Maybe we want an empty list in the "default" case? This would be in line with the other asType() functions.
        switch value {
        case .NodeSet(let nodes): return nodes
        default: return nil
