constexpr writer()

in src/libraries/csv/include/m/csv/writer.h [32:33]

• 2 lines of code
• 1 McCabe index (conditional complexity)

            constexpr writer(output_back_iter_t& iter) noexcept:
                m_iter(iter), m_field_quoter(iter), m_first_field{true}, m_first_row{true}