code: def __send_main_file(self, file_name):
          
  
          file_name = join(self.app.static_folder, file_name)
  
          with codecs.open(file_name, 'r', 'utf-8') as file:
              data = file.read()
  
          data = data.replace(
              'fields.article.url = apiProject.url + fields.article.url;',
              '''if (fields.article.url.substr(0, 4).toLowerCase() !== \'http\')
                          fields.article.url = apiProject.url + fields.article.url;''')
  
          headers = Headers()
          headers['Content-Length'] = getsize(file_name)
  
          response = self.app.response_class(data,
                                             mimetype=mimetypes.guess_type(file_name)[0],
                                             headers=headers,
                                             direct_passthrough=True)
  
          response.last_modified = int(getmtime(file_name))
  
          return response
docs: Send apidoc files from the apidoc folder to the browser.
          This method replaces all absolute urls in the file by
          the current url.
          :param file_name: the apidoc file.