Add time to a date

import std/times

let
  today = "20260503"
  dt: DateTime = parse(today, "yyyyMMdd")
  tomorrow = dt + 1.days
  yesterday = dt - 1.days

echo tomorrow                       # 2026-05-04T00:00:00+02:00
echo tomorrow.format("yyyyMMdd")    # 20260504

echo yesterday                      # 2026-05-02T00:00:00+02:00
echo yesterday.format("yyyyMMdd")   # 20260502

let next_week = dt + 1.weeks
echo next_week.format("yyyyMMdd")   # 20260510