class_docstr: Import tensorflow model to nnp model.
      
class_docstr_tok: ["Import","tensorflow","model","to","nnp","model","."]
code: def load_checkpoint_v1(self):
      ckpt_path = os.path.dirname(self._tf_file)
      latest_ckpt = tf.train.latest_checkpoint(ckpt_path)
      saver = tf.train.import_meta_graph(latest_ckpt + ".meta")
      with tf.Session() as session:
          session.run(
              [
                  tf.global_variables_initializer(),
                  tf.local_variables_initializer(),
              ]
          )
          saver.restore(session, latest_ckpt)
          graph_def = session.graph.as_graph_def(add_shapes=True)
      frozen_graph = freeze_graph.freeze_graph_with_def_protos(
          input_graph_def=graph_def,
          input_saver_def=None,
          input_checkpoint=latest_ckpt,
          output_node_names=self._outputs,
          restore_op_name="",
          filename_tensor_name="",
          output_graph=None,
          clear_devices=True,
          initializer_nodes="",
      )
      return frozen_graph
  
file_path: nnabla/python/src/nnabla/utils/converter/tensorflow/importer.py
imports: import os
  import tensorflow
  import tflite
  import tflite2onnx
  from tensorflow.core.framework import graph_pb2
  from tensorflow.python.tools import freeze_graph
  from tf2onnx import constants, tf_loader, optimizer
  from tf2onnx.tfonnx import process_tf_graph
  from .common import find_out_terminal_node
  from ..onnx import OnnxImporter
label_desc: Use image node_id 3 for calling the TensorflowImporter obj's underlying member method code with example usage: obj.load_checkpoint_v1() and returns: frozen_graph