Function write_escaped_string

include/fmt/format.h:1850–1863

template <typename Char, typename OutputIt>
auto write_escaped_string(OutputIt out, basic_string_view<Char> str)
    -> OutputIt {
  *out++ = static_cast<Char>('"');
  auto begin = str.begin(), end = str.end();
  do {
    auto escape = find_escape(begin, end);
    out = copy<Char>(begin, escape.begin, out);
    begin = escape.end;
    if (!begin) break;
    out = write_escaped_cp<OutputIt, Char>(out, escape);
  } while (begin != end);
  *out++ = static_cast<Char>('"');
  return out;
}

template <typename Char, typename OutputIt>
auto write_escaped_char(OutputIt out, Char v) -> OutputIt {