Currently, the multisig descriptor constructions are limited to 16 keys only possibly because of template parsing reasons. Under p2sh context, such scripts would be invalid anyway because of 520-byte rule, but we can support up to 20 keys for CHECKMULTISIG in witness script context. 


} 
bool CheckChecksum(Span<const char>& sp, bool require_checksum, std::string& error, std::string* out_checksum = nullptr)
{
    using namespace spanparsing;
    auto check_split = Split(sp, '#');
    if (check_split.size() > 2) {
        error = "Multiple '#' symbols";
        return false;
    }
    if (check_split.size() == 1 && require_checksum){
        error = "Missing checksum";
        return false;
    }
    if (check_split.size() == 2) {
        if (check_split[1].size() != 8) {
            error = strprintf("Expected 8 character checksum, not %u characters", check_split[1].size());
            return false;
        }
    }
    auto checksum = DescriptorChecksum(check_split[0]);
    if (checksum.empty()) {
        error = "Invalid characters in payload";
        return false;
    }
    if (check_split.size() == 2) {
        if (!std::equal(checksum.begin(), checksum.end(), check_split[1].begin())) {
            error = strprintf("Provided checksum '%s' does not match computed checksum '%s'", std::string(check_split[1].begin(), check_split[1].end()), checksum);
            return false;
        }
    }