code: def get_tone(s):
      if re.match(r".?[àằầèềìòồờùừỳ].*", s):
          return "acute"  # huyền
  
      if re.match(r".?[áắấéếíóốớúứý].*", s):
          return "grave"  # sắc
  
      if re.match(r".?[ảẳẩẻểỉỏổởủửỷ].*", s):
          return "hook"  # hỏi
  
      if re.match(r".?[ãẵẫẽễĩõỗỡũữỹ].*", s):
          return "tilde"  # ngã
  
      if re.match(r".?[ạặậẹệịọộợụựỵ].*", s):
          return "dot"  # nặng
  
      if re.match(r".?[aăâeêioôơuưy].*", s):
          return "blank"  # ngang
  
      return None
  
file_path: underthesea/examples/text_normalize/process_viwiktionary.py
imports: from os.path import join
  from underthesea.file_utils import DATASETS_FOLDER
  from underthesea.pipeline.word_tokenize.regex_tokenize import VIETNAMESE_CHARACTERS_LOWER, VIETNAMESE_VOWELS_LOWER
  import re
label_desc: Use image node_id 3 for calling a global function with example usage: get_tone(s) and returns: None, str, str, str, str, str, str