docs: def strftime(dt, fmt):
      '''
      `strftime` implementation working before 1900
      '''
      if _illegal_s.search(fmt):
          raise TypeError("This strftime implementation does not handle %s")
      if dt.year > 1900:
          return dt.strftime(fmt)
  
      fmt = fmt.replace('%c', '%a %b %d %H:%M:%S %Y')\
               .replace('%Y', str(dt.year))\
               .replace('%y', '{:04}'.format(dt.year)[-2:])
  
      year = dt.year
      # For every non-leap year century, advance by
      # 6 years to get into the 28-year repeat cycle
      delta = 2000 - year
      off = 6*(delta // 100 + delta // 400)
      year = year + off
  
      # Move to around the year 2000
      year = year + ((2000 - year)//28)*28
      timetuple = dt.timetuple()
      return time.strftime(fmt, (year,) + timetuple[1:])