import * as mod from "https://firstname.lastname@example.org/datetime/mod.ts";
Get number of the day in the year
Calculate difference between two dates.
Format date using format string
Check given year is a leap year or not. based on : https://docs.microsoft.com/en-us/office/troubleshoot/excel/determine-a-leap-year
Parse date from string using format string
Parse a date to return a IMF formatted string date RFC: https://tools.ietf.org/html/rfc7231#section-18.104.22.168 IMF is the time format to use when generating times in HTTP headers. The time being formatted must be in UTC for Format to generate the correct format.
Get number of the week in the year (ISO-8601)