Are you familiar with Rust, Haskell, C# or JavaScript? All of these allow creating new extension methods of existing types, albeit by three different methods.

Are you familiar with Rust, Haskell, C# or JavaScript? All of these allow creating new extension methods of existing types, albeit by three different methods. I'm assuming that your "2001.to_year - 1" is "the date time for 2001 minus 1 day" rust (traits) (pow::<BigInt>(2u8, 1000).digits().sum() (2..10_000).amicable_numbers().sum() 1901.to_year().upto(2001.to_year() - 1.to_day()).days().iter().filter(|d| d.mday + d.wday == 1).count() Haskell (type classes) sum . digits $ 2 ^ 1000 sum $ amicable_numbers [2..10000] count $ filter (\d -> mday d + wday d == 1) [year 1901 .. year 2000 - day 1] C# (extension methods) BigInteger.Pow(2, 1000).digits().sum() Enumerable.range(2,10000).amicable_numbers().sum() 1901.ToYear().UpTo(2001.ToYear() - 1.ToDay()).Days().Where(d => d.mday + d.wday == 1).Count() JavaScript (changing prototypes) bigInt(2).pow(1000).digits().sum() _.range(2, 10000).amicable_numbers().sum() 1901.to_year().upto(2001.to_year().minus(1)).days().filter(d => d.mday + d.wday === 1).length()