class_docstr: atis data class for nlu joint task.
code: def __init__(self, project_dir):
      super().__init__(project_dir)
      self.train_file = "train.txt"
      self.test_file = "test.txt"
      self.data_files = [self.train_file, self.test_file]
      self.config_files = ["atis_nlu_joint_lstm_crf.yml"]
      self.download_files = ["atis.train.pkl", "atis.test.pkl"]
  
file_path: delta/delta/data/datasets/atis.py
imports: import os
  import traceback
  import wget
  from absl import logging
  from delta.data.datasets.base_dataset import BaseDataSet
  from delta.data.datasets.utils import summary_joint_nlu_data
  from delta.utils.register import registers
label_desc: Use image node_id 1 to create a new ATIS object from inherited base classes: BaseDataSet with example: obj = ATIS(project_dir)