Gets human readable credential by the given id.

    :param wallet_handle: wallet handler (created by open_wallet).
    :param cred_id: Identifier by which requested credential is stored in the wallet
    :return:  credential json
     {
         "referent": string, // cred_id in the wallet
         "attrs": {"key1":"raw_value1", "key2":"raw_value2"},
         "schema_id": string,
         "cred_def_id": string,
         "rev_reg_id": Optional<string>,
         "cred_rev_id": Optional<string>
     }

async def prover_get_credential(wallet_handle: int,
                                cred_id: str) -> str:
    """
    Gets human readable credential by the given id.

    :param wallet_handle: wallet handler (created by open_wallet).
    :param cred_id: Identifier by which requested credential is stored in the wallet
    :return:  credential json
     {
         "referent": string, // cred_id in the wallet
         "attrs": {"key1":"raw_value1", "key2":"raw_value2"},
         "schema_id": string,
         "cred_def_id": string,
         "rev_reg_id": Optional<string>,
         "cred_rev_id": Optional<string>
     }
    """

    logger = logging.getLogger(__name__)
    logger.debug("prover_get_credential: >>> wallet_handle: %r, cred_id: %r",
                 wallet_handle,
                 cred_id)

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

    c_wallet_handle = c_int32(wallet_handle)
    c_cred_id = c_char_p(cred_id.encode('utf-8'))

    credentials_json = await do_call('indy_prover_get_credential',
                                     c_wallet_handle,
                                     c_cred_id,
                                     prover_get_credential.cb)

    res = credentials_json.decode()
    logger.debug("prover_get_credential: <<< res: %r", res)
    return res