docs: def parse_config_file():
      """
      Find the .tagcube config file in the current directory, or in the
      user's home and parse it. The one in the current directory has precedence.
      
      :return: A tuple with:
                  - email
                  - api_token
      """
      for filename in ('.tagcube', os.path.expanduser('~/.tagcube')):
  
          filename = os.path.abspath(filename)
  
          if not os.path.exists(filename):
              msg = 'TagCube configuration file "%s" does not exist'
              cli_logger.debug(msg % filename)
              continue
  
          msg = 'Parsing tagcube configuration file "%s"'
          cli_logger.debug(msg % filename)
  
          email, api_key = _parse_config_file_impl(filename)
          if email is not None and api_key is not None:
              msg = ('Found authentication credentials:\n'
                     '    email: %s\n'
                     '    api_key: %s')
              tokenized_api_key = '%s...%s' % (api_key[:3], api_key[-3:])
              args = (email, tokenized_api_key)
              cli_logger.debug(msg % args)
  
              return email, api_key
          else:
              msg = 'Configuration file does not contain credentials'
              cli_logger.debug(msg)
      else:
          return None, None