code: def ensure_fixed_length_bytes(var):
      
      dims, data, attrs, encoding = unpack_for_encoding(var)
      if check_vlen_dtype(data.dtype) == bytes:
          # TODO: figure out how to handle this with dask
          data = np.asarray(data, dtype=np.string_)
      return Variable(dims, data, attrs, encoding)
docs: Ensure that a variable with vlen bytes is converted to fixed width.