parse a boolean frame

def bool(self, name):
        """parse a boolean frame"""
        self._assert_is_string(name)
        frame = self._next_frame()
        if len(frame) != 1:
            raise MessageParserError("Expected exacty 1 byte for boolean value")
        val = frame != b"\x00"
        self.results.__dict__[name] = val
        return self