old_contents: # -*- coding: utf-8 -*-
  import pathlib
  from hashlib import sha512
  
  
  class BloArticle:
      """Article of Blo. written markdown style.
      """
      def __init__(self):
          self.raw_text = ''
          self.html_text = ''
          self.hs = sha512()
  
      def load_from_file(self, file_path):
          """ The main markdown contents oad from file.
          :param file_path: path to target markdown file. if file_path is not exists then raise FileNotFoundError.
          """
          if pathlib.Path(file_path).exists():
              with open(file_path) as f:
                  self.raw_text = f.readlines()
          else:
              raise FileNotFoundError()
  
      def convert_to_html(self):
          pass
  
      def get_digest(self):
          self.hs.update(self.html_text.encode('utf-8'))
          return  self.hs.digest()
  
  
new_contents: # -*- coding: utf-8 -*-
  import pathlib
  import CommonMark
  from hashlib import sha512
  
  
  class BloArticle:
      """Article of Blo. written markdown style.
      """
      def __init__(self):
          self._raw_text = ''
          self._html_text = ''
          self.hs = sha512()
  
      def load_from_file(self, file_path):
          """ The main markdown contents oad from file.
  
          :param file_path: path to target markdown file. if file_path is not exists then raise FileNotFoundError.
          """
          if pathlib.Path(file_path).exists():
              with open(file_path) as f:
                  self._raw_text = f.readlines()
          else:
              raise FileNotFoundError()
  
      def convert_to_html(self, template_name=""):
          """ Convert from raw markdown text to html.
  
          :param template_name: Jinja template file name (find on templates directory), default is empty
          :return: html formatted text
          """
          if template_name == "":
              self._html_text = CommonMark.commonmark(self._raw_text)
          else:
              # TODO: implement generate from markdown to jinja template applied html text
              pass
  
          return self._html_text
  
      def get_digest(self):
          self.hs.update(self._html_text.encode('utf-8'))
          return  self.hs.digest()
  
  
subject: Add html formatter method.