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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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