class_docstr: Bi-LSTM NER model with CRF classification layer (tf.keras model)
  
  Args:
      use_cudnn (bool, optional): use cudnn LSTM cells
code: def _rnn_cell(self, units, **kwargs):
      if self.use_cudnn:
          rnn_cell = tf.keras.layers.CuDNNLSTM(units, **kwargs)
      else:
          rnn_cell = tf.keras.layers.LSTM(units, **kwargs)
      return rnn_cell
  
file_path: nlp-architect/nlp_architect/models/ner_crf.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import tensorflow
  from nlp_architect.nn.tensorflow.python.keras.layers.crf import CRF
  from nlp_architect.nn.tensorflow.python.keras.utils import load_model, save_model
label_desc: Use image node_id 3 for calling the NERCRF obj's underlying member method code with example usage: obj._rnn_cell(units) and returns: rnn_cell