docs: def _schema_getter(self, db):
          """Retrieve a dictionary representing a database's data schema."""
          # Change DB connection if needed
          if self.database != db:
              self.change_db(db)
          schema_dict = {tbl: self.get_schema(tbl) for tbl in self.tables}
  
          schema_lst = []
          for table, schema in schema_dict.items():
              for col in schema:
                  col.insert(0, table)
                  schema_lst.append(col)
          return schema_lst