text: BigQueryLoader(    BASE_QUERY,    page_content_columns=["dna_sequence", "organism"],    metadata_columns=["id"],)data = loader.load()print(data)    [Document(page_content='dna_sequence: ATTCGA\norganism: Lokiarchaeum sp. (strain GC14_75).', lookup_str='', metadata={'id': 1}, lookup_index=0), Document(page_content='dna_sequence: AGGCGA\norganism: Heimdallarchaeota archaeon (strain LC_2).', lookup_str='', metadata={'id': 2}, lookup_index=0), Document(page_content='dna_sequence: TCCGGA\norganism: Acidianus hospitalis (strain W1).', lookup_str='', metadata={'id': 3}, lookup_index=0)]Adding Source to Metadataâ€‹# Note that the `id` column is being returned twice, with one instance aliased as `source`ALIASED_QUERY = """SELECT  id,  dna_sequence,  organism,  id as sourceFROM (  SELECT    ARRAY (    SELECT      AS STRUCT 1 AS id, "ATTCGA" AS dna_sequence, "Lokiarchaeum sp. (strain GC14_75)." AS organism    UNION ALL    SELECT      AS STRUCT 2 AS id, "AGGCGA" AS dna_sequence, "Heimdallarchaeota archaeon (strain LC_2)." AS organism    UNION ALL    SELECT      AS STRUCT 3 AS id, "TCCGGA" AS dna_sequence, "Acidianus hospitalis (strain W1)." AS organism) AS new_array),  UNNEST(new_array)"""loader = BigQueryLoader(ALIASED_QUERY, metadata_columns=["source"])data =