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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def metadata(self, run_id=None):
 """Provide metadata on a Ding0 run Parameters run_id: str, (defaults to current date) Distinguish multiple versions of Ding0 data by a `run_id`. If not set it defaults to current date in the format YYYYMMDDhhmmss Returns ------- dict Metadata """


        # Get latest version and/or git commit hash
        try:
            version = subprocess.check_output(
                ["git", "describe", "--tags", "--always"]).decode('utf8')
        except:
            version = None

        # Collect names of database table used to run Ding0 and data version
        if self.config['input_data_source']['input_data'] == 'versioned':
            data_version = self.config['versioned']['version']
            database_tables = self.config['versioned']
        elif self.config['input_data_source']['input_data'] == 'model_draft':
            data_version = 'model_draft'
            database_tables = self.config['model_draft']
        else:
            data_version = 'unknown'
            database_tables = 'unknown'

        # Collect assumptions
        assumptions = {}
        assumptions.update(self.config['assumptions'])
        assumptions.update(self.config['mv_connect'])
        assumptions.update(self.config['mv_routing'])
        assumptions.update(self.config['mv_routing_tech_constraints'])

        # Determine run_id if not set
        if not run_id:
            run_id = datetime.now().strftime("%Y%m%d%H%M%S")

        # Set instance attribute run_id
        if not self._run_id:
            self._run_id = run_id

        # Assing data to dict
        metadata = dict(
            version=version,
            mv_grid_districts=[int(_.id_db) for _ in self._mv_grid_districts],
            database_tables=database_tables,
            data_version=data_version,
            assumptions=assumptions,
            run_id=self._run_id
        )

        return metadata