'Get the schema for a given datset.table.
see https://cloud.google.com/bigquery/docs/reference/v2/tables#resource
:param dataset_id: the dataset ID of the requested table
:param table_id: the table ID of the requested table
:return: a table schema'

def get_schema(self, dataset_id, table_id):

    tables_resource = self.service.tables().get(projectId=self.project_id, datasetId=dataset_id, tableId=table_id).execute()
    return tables_resource['schema']
