def mime_type(self):
        """
        :return: String describing the mime type of this file (based on the filename)
        :note: Defaults to 'text/plain' in case the actual file type is unknown. """
        guesses = None
        if self.path:
            guesses = guess_type(self.path)
        return guesses and guesses[0] or self.DEFAULT_MIME_TYPE