Merge two revocation registry deltas (returned by issuer_create_credential or issuer_revoke_credential) to accumulate common delta.
    Send common delta to ledger to reduce the load.

    :param rev_reg_delta_json: revocation registry delta json
    :param other_rev_reg_delta_json: revocation registry delta for which PrevAccum value  is equal to current accum value of rev_reg_delta_json.
    :return: Merged revocation registry delta

async def issuer_merge_revocation_registry_deltas(rev_reg_delta_json: str,
                                                  other_rev_reg_delta_json: str) -> str:
    """
    Merge two revocation registry deltas (returned by issuer_create_credential or issuer_revoke_credential) to accumulate common delta.
    Send common delta to ledger to reduce the load.

    :param rev_reg_delta_json: revocation registry delta json
    :param other_rev_reg_delta_json: revocation registry delta for which PrevAccum value  is equal to current accum value of rev_reg_delta_json.
    :return: Merged revocation registry delta
    """

    logger = logging.getLogger(__name__)
    logger.debug(
        "issuer_merge_revocation_registry_deltas: >>> rev_reg_delta_json: %r, other_rev_reg_delta_json: %r",
        rev_reg_delta_json,
        other_rev_reg_delta_json)

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

    c_rev_reg_delta_json = c_char_p(rev_reg_delta_json.encode('utf-8'))
    c_other_rev_reg_delta_json = c_char_p(other_rev_reg_delta_json.encode('utf-8'))

    merged_revoc_reg_delta_json = await do_call('indy_issuer_merge_revocation_registry_deltas',
                                                c_rev_reg_delta_json,
                                                c_other_rev_reg_delta_json,
                                                issuer_merge_revocation_registry_deltas.cb)
    res = merged_revoc_reg_delta_json.decode()
    logger.debug("issuer_merge_revocation_registry_deltas: <<< res: %r", res)
    return res