def unlink(self):
        """
        Overrides orm unlink method.
        @param self: The object pointer
        @return: True/False.
        """
        for reserv_rec in self:
            if reserv_rec.state != 'draft':
                raise ValidationError(_('You cannot delete Reservation in %s\
                                         state.') % (reserv_rec.state))
        return super(HotelReservation, self).unlink()
Overrides orm unlink method.
        @param self: The object pointer
        @return: True/False.