return null;
String s = argumentList.e.evalString(vn); return normalize(s);
	private String normalizeSpace(VTDNav vn){	    if (argCount()== 0){	        return null;	    } else if (argCount() == 1){	        return null;	    }	    throw new IllegalArgumentException		("normalize-space()'s argument count is invalid");	    //return null;	}