Edit Decorator.py to probe on its shape and contents.

                metric_data = method_to_metric_fields.setdefault(method_name, dict()).setdefault(metric_name, dict())

                child_samples = raw_metric_data._child_samples()

                for sample in child_samples:

                    print(type(sample))

                    print(len(sample))

                    print(sample)

                    field_name, labels, value, _, _ = sample

                    if field_name == '_bucket': bucket_bounds.add(labels['le'])

                    if len(labels) > 0: field_name = '{:s}:{:s}'.format(field_name, json.dumps(labels, sort_keys=True))