Return a json dictionary representing this model.

def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'type') and self.type is not None:
            _dict['type'] = self.type
        if hasattr(self, 'text') and self.text is not None:
            _dict['text'] = self.text
        if hasattr(self, 'relevance') and self.relevance is not None:
            _dict['relevance'] = self.relevance
        if hasattr(self, 'mentions') and self.mentions is not None:
            _dict['mentions'] = [x._to_dict() for x in self.mentions]
        if hasattr(self, 'count') and self.count is not None:
            _dict['count'] = self.count
        if hasattr(self, 'emotion') and self.emotion is not None:
            _dict['emotion'] = self.emotion._to_dict()
        if hasattr(self, 'sentiment') and self.sentiment is not None:
            _dict['sentiment'] = self.sentiment._to_dict()
        if hasattr(self, 'disambiguation') and self.disambiguation is not None:
            _dict['disambiguation'] = self.disambiguation._to_dict()
        return _dict