return CStdType.Null;
return CStdType.Void;
    public static CType getJoinerType(FlatNode joiner)     {	boolean found;	//search backward until we find the first filter	while (!(joiner == null || joiner.contents instanceof SIRFilter)) {	    found = false;	    for (int i = 0; i < joiner.inputs; i++) {		if (joiner.incoming[i] != null) {		    joiner = joiner.incoming[i];		    found = true;		}	    }	    if (!found)		Utils.fail("cannot find any upstream filter from " + joiner.contents.getName());	}	if (joiner != null) 	    return ((SIRFilter)joiner.contents).getOutputType();	else 	    return CStdType.Null;    }