std::chrono::year::is_leap
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                    | constexpr bool is_leap() const noexcept; | (since C++20) | |
Determines if *this represents a leap year in the proleptic Gregorian calendar.
*this represents a leap year if the stored year value
- is divisible by 4 and not divisible by 100; or
- is divisible by 400.
Return value
true if *this represents a leap year, otherwise false.