Method flush

include/fmt/base.h:1933–1939

  }

  void flush() {
    auto size = this->size();
    this->clear();
    const T* begin = data_;
    const T* end = begin + this->limit(size);
    out_ = copy<T>(begin, end, out_);
  }

 public:
  explicit iterator_buffer(OutputIt out, size_t n = buffer_size)