text: import json
  
  # files = ["../data/train19_dev.json", "../data/train19_train.json", "../data/train19_test.json", "train_large.json"]
  files = ["../data/train19_dev.json",  "../data/train19_test.json", "train_small.json",  "train_large.json"]
  
  def read(file, start_id=0):
      with open(file, 'r', encoding='utf-8') as f:
          train = json.load(f)
          trainx = []
          for dic in train:
              dic['_id'] = start_id
              trainx.append(dic)
              start_id += 1
      return trainx
  
  result = []
  with open('data2/train_full.json', 'w', encoding='utf-8') as fw:
      startid = 0
      for file in files:
          fdic = read(file, start_id=startid)
          startid += len(fdic)
          result.extend(fdic)
      json.dump(result, fw, indent=4, ensure_ascii=False)
  print('FIN')