std::chrono::operator ==,!=,<,<=,>,>= (std::chrono::year_month)
From cppreference.com
                    
                                        
                    < cpp | chrono | year month
                    
                                                            
                    | constexpr bool operator==(const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (1) | (since C++20) | 
| constexpr bool operator!=(const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (2) | (since C++20) | 
| constexpr bool operator< (const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (3) | (since C++20) | 
| constexpr bool operator> (const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (4) | (since C++20) | 
| constexpr bool operator<=(const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (5) | (since C++20) | 
| constexpr bool operator>=(const std::chrono::year_month& x, const std::chrono::year_month& y) noexcept; | (6) | (since C++20) | 
Compares the two year_month objects x and y.
Return value
1) x.year() == y.year() && x.month() == y.month()
2) !(x == y)
3) x.year() < y.year() || (x.year() == y.year() && x.month() < y.month())
4) y < x
5) !(y < x)
6) !(x < y)