presto-main/src/main/java/io/prestosql/operator/ScanFilterAndProjectOperator.java/ScanFilterAndProjectOperator/close
class ScanFilterAndProjectOperator:    @Override
    public void close()
    {
        if (pageSource != null) {
            try {
                pageSource.close();
            }
            catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }
        else if (cursor != null) {
            cursor.close();
        }
    }