How should I use rnn_cell.py?

[yangchangli]

Hello, I have some questions to ask you.
How should I use rnn_cell.py?
Is it like the normal LSTM() method in TensorFlow?
A
...
Lstm = LSTM(50,return_sequence = False)(input)
...

B
...
From rnn_cell import NLSTMCell
Cell = NLSTMCell(num_units=3, depth=2)
#init_state = cell.zero_state(batch_size, dtype=tf.float32)
Output, new_state = cell(inputs, state=init_state)
...

What is init_state used for?