code: def get_tensor_info(self):
      
      # Add the additional length dimension to every shape
  
      def add_length_dim(tensor_info):
        return feature_lib.TensorInfo(
            shape=(self._length,) + tensor_info.shape,
            dtype=tensor_info.dtype,
        )
  
      tensor_info = super(SequenceDict, self).get_tensor_info()
      return utils.map_nested(add_length_dim, tensor_info)
docs: See base class for details.