code: def dateint_week_by_dateint(dateint, first_day='Monday'):
      
      weekday_ix = dateint_to_weekday(dateint, first_day)
      first_day_dateint = shift_dateint(dateint, -weekday_ix)
      last_day_dateint = shift_dateint(first_day_dateint, 6)
      return dateint_range(first_day_dateint, last_day_dateint)
docs: Return a dateint range of the week the given dateint belongs to.
  
      Arguments
      ---------
      dateint : int
          An integer object decipting a specific calendaric day; e.g. 20161225.
      first_day : str, default 'Monday'
          The first day of the week.
  
      Returns
      -------
      iterable
          An iterable of dateint representing all days of the week the given
          dateint belongs to.