Initialize a MetricResponse object from a json dictionary.

def _from_dict(cls, _dict):
        """Initialize a MetricResponse object from a json dictionary."""
        args = {}
        if 'aggregations' in _dict:
            args['aggregations'] = [
                MetricAggregation._from_dict(x)
                for x in (_dict.get('aggregations'))
            ]
        return cls(**args)