class_docstr: Executes a direct download of data from Yahoo servers for the given time
  range.
  
  Specific parameters (or specific meaning):
  
    - ``dataname``
  
      The ticker to download ('YHOO' for Yahoo own stock quotes)
  
    - ``proxies``
  
      A dict indicating which proxy to go through for the download as in
      {'http': 'http://myproxy.com'} or {'http': 'http://127.0.0.1:8080'}
  
    - ``period``
  
      The timeframe to download data in. Pass 'w' for weekly and 'm' for
      monthly.
  
    - ``reverse``
  
      [2018-11-16] The latest incarnation of Yahoo online downloads returns
      the data in the proper order. The default value of ``reverse`` for the
      online download is therefore set to ``False``
  
    - ``adjclose``
  
      Whether to use the dividend/split adjusted close and adjust all values
      according to it.
  
    - ``urlhist``
  
      The url of the historical quotes in Yahoo Finance used to gather a
      ``crumb`` authorization cookie for the download
  
    - ``urldown``
  
      The url of the actual download server
  
    - ``retries``
  
      Number of times (each) to try to get a ``crumb`` cookie and download
      the data
  
    
code: def start(self):
      self.start_v7()
  
      # Prepared a "path" file -  CSV Parser can take over
      super(YahooFinanceData, self).start()
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import collections
  from datetime import date, datetime
  import io
  import itertools
  from ..utils.py3 import urlopen, urlquote, ProxyHandler, build_opener, install_opener
  import backtrader
  from ..None import feed
  from ..utils import date2num
label_desc: Use image node_id 2 for calling the YahooFinanceData obj's underlying member method code with example usage: obj.start() without return types