Method operator !=

unittests/catch.hpp:9702–9704

            (std::strncmp( m_start, other.m_start, size() ) == 0);
    }
    auto StringRef::operator != ( StringRef const& other ) const noexcept -> bool {
        return !operator==( other );
    }

    auto StringRef::operator[](size_type index) const noexcept -> char {
        return m_start[index];