Method begin

Tools/CheckVector.h:79–79

    void reserve(size_t new_size) { full.reserve(start + new_size); }

    auto begin() { return full.begin() + start; }
    auto end() { return full.begin() + finish; }
    auto begin() const { return full.begin() + start; }
    auto end() const { return full.begin() + finish; }