code: def subword_tokenize(text: str, engine: str = "tcc") -> List[str]:
      
      if not text or not isinstance(text, str):
          return []
  
      if engine == "etcc":
          from .etcc import segment
      else:  # default
          from .tcc import segment
  
      return segment(text)
docs: :param str text: text to be tokenized
      :param str engine: subword tokenizer
      :return: list of subwords
  
      **Options for engine**
          * tcc (default) -  Thai Character Cluster (Theeramunkong et al. 2000)
          * etcc - Enhanced Thai Character Cluster (Inrut et al. 2001) [In development]