code: def writetofile(self, filename):
      if not self.datafile:
          return
  
      if not hasattr(filename, "read"):
          # It's not a file - open it
          f = io.open(filename, "w")
      else:
          f = filename
  
      self.datafile.seek(0)
      for line in self.datafile:
          f.write(line)
  
      f.close()
  
file_path: backtrader/tools/yahoodownload.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import collections
  import datetime
  import io
  import logging
  import sys
label_desc: Use image node_id 2 for calling the YahooDownload obj's underlying member method code with example usage: obj.writetofile(filename) without return types