Given a name, find its DID (decentralized identifier) information.
        Returns {'address': ..., 'index': ...}
        Returns None if there is no such name

def get_name_DID_info(self, name, lastblock=None):
        """
        Given a name, find its DID (decentralized identifier) information.
        Returns {'address': ..., 'index': ...}
        Returns None if there is no such name
        """
        if lastblock is None:
            lastblock = self.lastblock

        cur = self.db.cursor()
        did_info = namedb_get_name_DID_info(cur, name, lastblock)
        if did_info is None:
            return None

        return did_info