Method replace_value

common/string-keyed.h:260–265

        return this->end() + 1;
    }
    void replace_value(std::string_view v) {
        auto nk = this->size();
        auto ptr = (char*) realloc((void*)this->data(), nk+1 + v.size()+1);
        do_copy(ptr + nk+1, v);
        assign({ptr, nk});
    }
};

template <class M>