Vocabulary
calendar

Inputs
timestampa timestamp


Outputs
[1,53]an integer


Word description
Calculates the ISO 8601 week number from 1 to 53 (leap years). See https://en.wikipedia.org/wiki/ISO_week_date

Examples
Last day of 2018 is already in the first week of 2019.
USING: calendar prettyprint ; 2018 12 31 <date> week-number .
1

2020 is a leap year with 53 weeks, and January 1st, 2021 is still in week 53 of 2020.
USING: calendar prettyprint ; 2021 1 1 <date> week-number .
53


Definition