presto-orc/src/main/java/io/prestosql/orc/OrcBlockFactory.java/OrcBlockLoader/load
class OrcBlockLoader:        @Override
        public final Block load()
        {
            checkState(!loaded, "Already loaded");
            checkState(currentPageId == expectedPageId, "ORC reader has been advanced beyond block");

            loaded = true;
            try {
                Block block = blockReader.readBlock();
                if (loadFully) {
                    block = block.getLoadedBlock();
                }
                return block;
            }
            catch (IOException | RuntimeException e) {
                throw exceptionTransform.apply(e);
            }
        }