code: def open_resource(self, filename, mode='r'):
          
          assert self.current_run is not None, "Can only be called during a run."
          return self.current_run.open_resource(filename, mode)
docs: Open a file and also save it as a resource.
  
          Opens a file, reports it to the observers as a resource, and returns
          the opened file.
  
          In Sacred terminology a resource is a file that the experiment needed
          to access during a run. In case of a MongoObserver that means making
          sure the file is stored in the database (but avoiding duplicates) along
          its path and md5 sum.
  
          This function can only be called during a run, and just calls the
          :py:meth:`sacred.run.Run.open_resource` method.
  
          Parameters
          ----------
          filename: str
              name of the file that should be opened
          mode : str
              mode that file will be open
  
          Returns
          -------
          file
              the opened file-object