def getBytesForString(self, u):
        """
        Returns the corresponding utf-8 encoded string for a given unicode
        object. If there is no string, one is encoded.

        @since: 0.6
        """
        h = hash(u)
        s = self._unicodes.get(h, None)

        if s is not None:
            return s

        s = self._unicodes[h] = u.encode('utf-8')

        return s
Returns the corresponding utf-8 encoded string for a given unicode
        object. If there is no string, one is encoded.

        @since: 0.6