I am constantly reusing the same date/time formulas, so I thought it would interesting to make an “uber”-datetime object.
My idea was: “What information can I 
squeeze out of JUST a single date/time?” (JUST the date/time–not passing in timezone or “Week starting on Monday, etc”)
This pack has a bit of overlap with the Coda date object, but my goal here is to create a mega-date object with a lot of helpful baked in formulas.
For the week formulas, I created one property for each day so you don’t have to remember if Monday is 0 or 1 in your formula 
. . . For example, EndOfWeekSunday means “End of Week Starting with Sunday”
Try it out and let me know if you have any feedback!
PACK PAGE
DEMO PAGE