class_docstr: Parses pre-downloaded Yahoo CSV Data Feeds (or locally generated if they
  comply to the Yahoo format)
  
  Specific parameters:
  
    - ``dataname``: The filename to parse or a file-like object
  
    - ``reverse`` (default: ``False``)
  
      It is assumed that locally stored files have already been reversed
      during the download process
  
    - ``adjclose`` (default: ``True``)
  
      Whether to use the dividend/split adjusted close and adjust all
      values according to it.
  
    - ``adjvolume`` (default: ``True``)
  
      Do also adjust ``volume`` if ``adjclose`` is also ``True``
  
    - ``round`` (default: ``True``)
  
      Whether to round the values to a specific number of decimals after
      having adjusted the close
  
    - ``roundvolume`` (default: ``0``)
  
      Round the resulting volume to the given number of decimals after having
      adjusted it
  
    - ``decimals`` (default: ``2``)
  
      Number of decimals to round to
  
    - ``swapcloses`` (default: ``False``)
  
      [2018-11-16] It would seem that the order of *close* and *adjusted
      close* is now fixed. The parameter is retained, in case the need to
      swap the columns again arose.
code: def start(self):
      super(YahooFinanceCSVData, self).start()
  
      if not self.params.reverse:
          return
  
      # Yahoo sends data in reverse order and the file is still unreversed
      dq = collections.deque()
      for line in self.f:
          dq.appendleft(line)
  
      f = io.StringIO(newline=None)
      f.writelines(dq)
      f.seek(0)
      self.f.close()
      self.f = f
  
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 1 for calling the YahooFinanceCSVData obj's underlying member method code with example usage: obj.start() without return types