def rev_reg_id(cd_id: str, tag: str) -> str:
return '<STR_LIT>'.format(cd_id.split('<STR_LIT::>', <NUM_LIT:1>)[<NUM_LIT:0>], cd_id, tag)<EOL>
Given a credential definition identifier and a tag, return the corresponding
revocation registry identifier, repeating the issuer DID from the
input identifier.

:param cd_id: credential definition identifier
:param tag: tag to use
:return: revocation registry identifier