def __init__(self, downloader=None):
    'Constructor. Receives an optional downloader.'
    self._ready = False
    self._x_forwarded_for_ip = None
    self.set_downloader(downloader)
Constructor. Receives an optional downloader.
def __init__(self, downloader=None):
    
    self._ready = False
    self._x_forwarded_for_ip = None
    self.set_downloader(downloader)