https://travis-ci.org/github/bitcoin/bitcoin/jobs/680452476#L6107
{
    return RPCHelpMan{"joinpsbts",
            "\nJoins multiple distinct PSBTs with different inputs and outputs into one PSBT with inputs and outputs from all of the PSBTs\n"
            "No input in any of the PSBTs can be in more than one of the PSBTs.\n",
            {
                {"txs", RPCArg::Type::ARR, RPCArg::Optional::NO, "The base64 strings of partially signed transactions",
                    {
                        {"psbt", RPCArg::Type::STR, RPCArg::Optional::NO, "A base64 string of a PSBT"}
                    }}
            },
            RPCResult {
                    RPCResult::Type::STR, "", "The base64-encoded partially signed transaction"
            },
            RPCExamples {
                HelpExampleCli("joinpsbts", "\"psbt\"")
            },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    RPCTypeCheck(request.params, {UniValue::VARR}, true);
    
    std::vector<PartiallySignedTransaction> psbtxs;
    UniValue txs = request.params[0].get_array();
    if (txs.size() <= 1) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, "At least two PSBTs are required to join PSBTs.");
    }
    uint32_t best_version = 1;