std::chrono::year_month_weekday::operator sys_days, std::chrono::year_month_weekday::operator local_days
From cppreference.com
                    
                                        
                    < cpp | chrono | year month weekday
                    
                                                            
                    | constexpr operator std::chrono::sys_days() const noexcept; | (1) | (since C++20) | 
| explicit constexpr operator std::chrono::local_days() const noexcept; | (2) | (since C++20) | 
Converts *this to a std::chrono::time_point representing the same date as this year_month_weekday.
1) If year().ok() && month().ok() && weekday().ok():
-  If index() == 0, returns a sys_daysthat represents the date 7 days prior to the first weekday() of the year and month.
-  Else, returns a sys_daysthat represents the date (index() - 1) * 7 days after the first weekday() of the year and month.
 
-  If index() == 0, returns a 
 Otherwise, the returned value is unspecified.
2) Same as (1), but returns 
local_days instead of sys_days. Equivalent to local_days(sys_days(*this).time_since_epoch()).