Initialize a ToneAnalysis object from a json dictionary.

def _from_dict(cls, _dict):
        """Initialize a ToneAnalysis object from a json dictionary."""
        args = {}
        if 'document_tone' in _dict:
            args['document_tone'] = DocumentAnalysis._from_dict(
                _dict.get('document_tone'))
        else:
            raise ValueError(
                'Required property \'document_tone\' not present in ToneAnalysis JSON'
            )
        if 'sentences_tone' in _dict:
            args['sentences_tone'] = [
                SentenceAnalysis._from_dict(x)
                for x in (_dict.get('sentences_tone'))
            ]
        return cls(**args)