Get the MIME type for a given stream of bytes

        :param buff: Stream of bytes
        :type buff: bytes

        :rtype: str

def _get_mime_type(self, buff):
        """Get the MIME type for a given stream of bytes

        :param buff: Stream of bytes
        :type buff: bytes

        :rtype: str

        """
        if self._magic is not None:
            return self._magic.id_buffer(buff)
        else:
            try:
                return mimetypes.guess_type("f." + imghdr.what(0, buff))[0]
            except (IOError, TypeError):
                logging.warning("Couldn't detect content type of avatar image"
                                ". Specify the 'contentType' parameter explicitly.")
                return None