Function begin

lesson6-Segmentation/json.hpp:20966–20971

! @brief returns an iterator to the first element Returns an iterator to the first element. @image html range-begin-end.svg "Illustration from cppreference.com" @return iterator to the first element @complexity Constant. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements:

    @since version 1.0.0
    */
    iterator begin() noexcept
    {
        iterator result(this);
        result.set_begin();
        return result;
    }

    /*!
    @copydoc basic_json::cbegin()