name(str, optional): The default value is None. Normally there is no need for user to set this property. For more information, please refer to :ref:`api_guide_Name`.
Returns:
Variable|list(Variable): Tensors returned by the callable from the first pair whose pred is True,
Tensor|list(Tensor): Tensors returned by the callable from the first pair whose pred is True,
or Tensors returned by ``default`` if no pred in ``pred_fn_pairs`` is True and ``default`` is not None,
or Tensors returned by the last callable in ``pred_fn_pairs`` if no pred in ``pred_fn_pairs`` is True and ``default`` is None.