def read uid
      grid_file = session.bucket.open(uid, 'r')
      meta = grid_file.metadata.each_with_object({}){ |(k,v), h| h[k.to_sym] = v }
      [ grid_file.read, meta ]

    rescue RuntimeError
      raise DataNotFound
    end
def read uid
      grid_file = session.bucket.open(uid, 'r')
      meta = grid_file.metadata.each_with_object({}){ |(k,v), h| h[k.to_sym] = v }
      [ grid_file.read, meta ]

    rescue RuntimeError
      raise DataNotFound
    end
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