code: def guess_mime_file_mime (file_prog, filename):
      
      mime, encoding = None, None
      cmd = [file_prog, "--brief", "--mime-type", filename]
      try:
          mime = backtick(cmd).strip()
      except OSError:
          # ignore errors, as file(1) is only a fallback
          pass
      if mime not in ArchiveMimetypes:
          mime, encoding = None, None
      return mime, encoding
docs: Determine MIME type of filename with file(1) and --mime option.
      @return: tuple (mime, encoding)