code: def metadata(self, run_id=None):
          
  
          # 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
docs: 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