Given a DID for subdomain, get the subdomain record
        Return {'record': ...} on success
        Return {'error': ...} on error

def get_subdomain_DID_record(self, did):
        """
        Given a DID for subdomain, get the subdomain record
        Return {'record': ...} on success
        Return {'error': ...} on error
        """
        try:
            did_info = parse_DID(did)
            assert did_info['name_type'] == 'subdomain'
        except Exception as e:
            if BLOCKSTACK_DEBUG:
                log.exception(e)

            return {'error': 'Invalid DID', 'http_status': 400}

        subrec = get_DID_subdomain(did, check_pending=True)
        if subrec is None:
            return {'error': 'Failed to load subdomain from {}'.format(did), 'http_status': 404}

        return {'record': subrec.to_json()}