code: def validate_backup_window(window):
      
  
      hour = r'[01]?[0-9]|2[0-3]'
      minute = r'[0-5][0-9]'
      r = ("(?P<start_hour>%s):(?P<start_minute>%s)-"
           "(?P<end_hour>%s):(?P<end_minute>%s)") % (hour, minute, hour, minute)
      range_regex = re.compile(r)
      m = range_regex.match(window)
      if not m:
          raise ValueError("DBInstance PreferredBackupWindow must be in the "
                           "format: hh24:mi-hh24:mi")
      start_ts = (int(m.group('start_hour')) * 60) + int(m.group('start_minute'))
      end_ts = (int(m.group('end_hour')) * 60) + int(m.group('end_minute'))
      if abs(end_ts - start_ts) < 30:
          raise ValueError("DBInstance PreferredBackupWindow must be at least "
                           "30 minutes long.")
      return window
docs: Validate PreferredBackupWindow for DBInstance