Method as_set

include/stringzilla/stringzilla.hpp:2597–2601

@brief Populate a character set with characters present in this string. */

    /**  @brief Populate a character set with characters present in this string. */
    byteset as_set() const noexcept {
        byteset set;
        for (auto c : *this) set.add(c);
        return set;
    }

  private:
    sz_constexpr_if_cpp14 string_slice &assign(string_view const &other) noexcept {