Revoke a credential identified by a cred_revoc_id (returned by issuer_create_credential).

    The corresponding credential definition and revocation registry must be already
    created an stored into the wallet.

    This call returns revoc registry delta as json file intended to be shared as REVOC_REG_ENTRY transaction.
    Note that it is possible to accumulate deltas to reduce ledger load.

    :param wallet_handle: wallet handler (created by open_wallet).
    :param blob_storage_reader_handle: pre-configured blob storage reader instance handle that will allow
    to read revocation tails
    :param rev_reg_id: id of revocation registry stored in wallet
    :param cred_revoc_id: local id for revocation info
    :return: Revocation registry delta json with a revoked credential.

async def issuer_revoke_credential(wallet_handle: int,
                                   blob_storage_reader_handle: int,
                                   rev_reg_id: str,
                                   cred_revoc_id: str) -> str:
    """
    Revoke a credential identified by a cred_revoc_id (returned by issuer_create_credential).

    The corresponding credential definition and revocation registry must be already
    created an stored into the wallet.

    This call returns revoc registry delta as json file intended to be shared as REVOC_REG_ENTRY transaction.
    Note that it is possible to accumulate deltas to reduce ledger load.

    :param wallet_handle: wallet handler (created by open_wallet).
    :param blob_storage_reader_handle: pre-configured blob storage reader instance handle that will allow
    to read revocation tails
    :param rev_reg_id: id of revocation registry stored in wallet
    :param cred_revoc_id: local id for revocation info
    :return: Revocation registry delta json with a revoked credential.
    """

    logger = logging.getLogger(__name__)
    logger.debug(
        "issuer_revoke_credential: >>> wallet_handle: %r, blob_storage_reader_handle: %r, rev_reg_id: %r, "
        "cred_revoc_id: %r",
        wallet_handle,
        blob_storage_reader_handle,
        rev_reg_id,
        cred_revoc_id)

    if not hasattr(issuer_revoke_credential, "cb"):
        logger.debug("issuer_revoke_credential: Creating callback")
        issuer_revoke_credential.cb = create_cb(CFUNCTYPE(None, c_int32, c_int32, c_char_p))

    c_wallet_handle = c_int32(wallet_handle)
    c_blob_storage_reader_handle = c_int32(blob_storage_reader_handle)
    c_rev_reg_id = c_char_p(rev_reg_id.encode('utf-8'))
    c_cred_revoc_id = c_char_p(cred_revoc_id.encode('utf-8'))

    revoc_reg_delta_json = await do_call('indy_issuer_revoke_credential',
                                         c_wallet_handle,
                                         c_blob_storage_reader_handle,
                                         c_rev_reg_id,
                                         c_cred_revoc_id,
                                         issuer_revoke_credential.cb)
    res = revoc_reg_delta_json.decode()
    logger.debug("issuer_revoke_credential: <<< res: %r", res)
    return res