Example documentation or code

Hey
I work with BigQuery at work, and I have been trying to analyze BigQuery sql statements. I want to parse them and create the AST trees. I got it working using the https://github.com/apstndb/zetasql-sandbox , but I run into problems creating the catalog. Do you guys have any example documentation on creating the catalog from BigQuery API or maybe even just mocking it

Thanks
Javier