def start()

in main_flow.py [0:0]


    def start(self):
        '''
        Metaflow flows must begin with a function called 'start.'
        So here's the start function.
        It prints out the input parameters to the job
        and initializes an experiment tracking run.
        '''
        import os

        print(os.getenv('GOOGLE_APPLICATION_CREDENTIALS'))

        print(f"Data Validation Origin: {self.data_validation_origin}")
        print(f"Data Validation Reporting Destination: {self.data_validation_reporting_destination}")

        self.next(self.retrieve_metrics)