class_docstr: Class that chains datas
class_docstr_tok: ["Class","that","chains","datas"]
docstr: To be overriden by subclasses which may auto-calculate the
  timezone
docstr_tok: ["To","be","overriden","by","subclasses","which","may","auto-calculate","the","timezone"]
code: def _gettz(self):
      """To be overriden by subclasses which may auto-calculate the
      timezone"""
      if self._args:
          return self._args[0]._gettz()
      return bt.utils.date.Localizer(self.p.tz)
  
file_path: backtrader/backtrader/feeds/chainer.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from datetime import datetime
  import backtrader
  from backtrader.utils.py3 import range
label_desc: Use image node_id 6 for calling the Chainer obj's underlying member method code with example usage: obj._gettz() and returns: bt, self