Initialize a Voices object from a json dictionary.

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