docs: def past_datetime_str(adatetime):
      """
      For adatetime is since 12:00AM, return: "Today at H:MM [A]PM"
      For adatetime is between 12:00AM and 11:59PM on yesterday:
                                      "Yesterday at 6:23 PM"
      For adatetime is between 2 and 6 days ago: "[2-6] days ago"
      For adatetime is 7 days ago: "1 week ago"
      For adatetime is 8-14 days ago: "Over 1 week ago"
      For adatetime is 15-21 days ago: "Over 2 weeks ago"
      For adatetime is 22-28 days ago: "Over 3 weeks ago"
      For adatetime is 29-56 days ago: "Over 1 month ago"
      For adatetime is 57-84 days ago: "Over 2 months ago"
      For adatetime is 85-112 days ago: "Over 3 months ago"
      and so on, in increments of 28 days, until T-365,
      at which point: "Over 1 year ago",
      then after another 365 days "Over 2 years ago", etc
      """
      if is_today(adatetime):
          return "today at {}".format(time_str(adatetime))
  
      if last_midnight() - adatetime <= timedelta(days=7):
          for day in range(1, 8):
              if is_days_ago(adatetime, day):
                  if day == 1:
                      return "yesterday at {}".format(time_str(adatetime))
                  if day == 7:
                      return "1 week ago"
                  return "{:.0f} days ago".format(day)
  
      if last_midnight() - adatetime <= timedelta(days=28):
          week = get_past_weeks_count(adatetime)
          if week == 1:
              return "over {:.0f} week ago".format(week)
          else:
              return "over {:.0f} weeks ago".format(week)
  
      if last_midnight() - adatetime <= timedelta(days=365):
          month = get_past_months_count(adatetime)
          if month == 1:
              return "over {:.0f} month ago".format(month)
          else:
              return "over {:.0f} months ago".format(month)
  
      year = get_past_years_count(adatetime)
      if year == 1:
          return "over {:.0f} year ago".format(year)
      else:
          return "over {:.0f} years ago".format(year)