docstr: Returns the iso week number of the next trading day, given a ``day``
  (datetime/date) instance
docstr_tok: ["Returns","the","iso","week","number","of","the","next","trading","day",",","given","a","``","day","``","(","datetime\/date",")","instance"]
code: def nextday_week(self, day):
      """
      Returns the iso week number of the next trading day, given a ``day``
      (datetime/date) instance
      """
      self._nextday(day)[1][1]
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from datetime import datetime, timedelta, time
  from .metabase import MetaParams
  from backtrader.utils.py3 import string_types, with_metaclass
  from backtrader.utils import UTC
label_desc: Use image node_id 4 for calling the TradingCalendarBase obj's underlying member method code with example usage: obj.nextday_week(day) without return types