docs: def sample_storage_size(self):
          """Get the storage size of the samples storage collection."""
  
          try:
              coll_stats = self.database.command('collStats', 'fs.chunks')
              sample_storage_size = coll_stats['size']/1024.0/1024.0
              return sample_storage_size
          except pymongo.errors.OperationFailure:
              return 0