Method append

src/fl/stl/json.cpp.hpp:1131–1133

    fl::deque<char>& out;

    void append(const char* str) {
        while (*str) { out.push_back(*str++); }
    }

    void append_str(const fl::string& str) {
        for (size_t i = 0; i < str.size(); ++i) {