@classmethod
def inject(cls, span, obj):
    """ Injects the span context into a `carrier` object.

        :param opentracing.span.SpanContext span: the SpanContext instance
        :param Any obj: Object to use as context
        """
    obj.metadata['__parent-span__'] = dict()
    cls.inject_span(span, obj.metadata['__parent-span__'])
