class_docstr: Executes a direct download of data from Quandl servers for the given time
  range.
  
  Specific parameters (or specific meaning):
  
    - ``dataname``
  
      The ticker to download ('YHOO' for example)
  
    - ``baseurl``
  
      The server url. Someone might decide to open a Quandl compatible
      service in the future.
  
    - ``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'}
  
    - ``buffered``
  
      If True the entire socket connection wil be buffered locally before
      parsing starts.
  
    - ``reverse``
  
      Quandl returns the value in descending order (newest first). If this is
      ``True`` (the default), the request will tell Quandl to return in
      ascending (oldest to newest) format
  
    - ``adjclose``
  
      Whether to use the dividend/split adjusted close and adjust all values
      according to it.
  
    - ``apikey``
  
      apikey identification in case it may be needed
  
    - ``dataset``
  
      string identifying the dataset to query. Defaults to ``WIKI``
  
    
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code: def start(self):
      self.error = None
  
      url = "{}/{}/{}.csv".format(
          self.p.baseurl, self.p.dataset, urlquote(self.p.dataname)
      )
  
      urlargs = []
      if self.p.reverse:
          urlargs.append("order=asc")
  
      if self.p.apikey is not None:
          urlargs.append("api_key={}".format(self.p.apikey))
  
      if self.p.fromdate:
          dtxt = self.p.fromdate.strftime("%Y-%m-%d")
          urlargs.append("start_date={}".format(dtxt))
  
      if self.p.todate:
          dtxt = self.p.todate.strftime("%Y-%m-%d")
          urlargs.append("end_date={}".format(dtxt))
  
      if urlargs:
          url += "?" + "&".join(urlargs)
  
      if self.p.proxies:
          proxy = ProxyHandler(self.p.proxies)
          opener = build_opener(proxy)
          install_opener(opener)
  
      try:
          datafile = urlopen(url)
      except IOError as e:
          self.error = str(e)
          # leave us empty
          return
  
      if datafile.headers["Content-Type"] != "text/csv":
          self.error = "Wrong content type: %s" % datafile.headers
          return  # HTML returned? wrong url?
  
      if self.params.buffered:
          # buffer everything from the socket into a local buffer
          f = io.StringIO(datafile.read().decode("utf-8"), newline=None)
          datafile.close()
      else:
          f = datafile
  
      self.f = f
  
      # Prepared a "path" file -  CSV Parser can take over
      super(Quandl, self).start()
  
file_path: backtrader/backtrader/feeds/quandl.py
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
  from ..None import feed
  from ..utils import date2num
label_desc: Use image node_id 1 for calling the Quandl obj's underlying member method code with example usage: obj.start() without return types