Initialize a Trait object from a json dictionary.

def _from_dict(cls, _dict):
        """Initialize a Trait object from a json dictionary."""
        args = {}
        if 'trait_id' in _dict:
            args['trait_id'] = _dict.get('trait_id')
        else:
            raise ValueError(
                'Required property \'trait_id\' not present in Trait JSON')
        if 'name' in _dict:
            args['name'] = _dict.get('name')
        else:
            raise ValueError(
                'Required property \'name\' not present in Trait JSON')
        if 'category' in _dict:
            args['category'] = _dict.get('category')
        else:
            raise ValueError(
                'Required property \'category\' not present in Trait JSON')
        if 'percentile' in _dict:
            args['percentile'] = _dict.get('percentile')
        else:
            raise ValueError(
                'Required property \'percentile\' not present in Trait JSON')
        if 'raw_score' in _dict:
            args['raw_score'] = _dict.get('raw_score')
        if 'significant' in _dict:
            args['significant'] = _dict.get('significant')
        if 'children' in _dict:
            args['children'] = [
                Trait._from_dict(x) for x in (_dict.get('children'))
            ]
        return cls(**args)