code: def open(self, url, mode='rb', reload=False, filename=None):
          
          if '://' not in url:
              path_that_might_be_relative = url
              path = os.path.join(self.directory, path_that_might_be_relative)
              return open(path, mode)
          if filename is None:
              filename = urlparse(url).path.split('/')[-1]
          path = self.path_to(filename)
          if reload and os.path.exists(path):
              os.remove(path)
          if not os.path.exists(path):
              download(url, path, self.verbose)
          return open(path, mode)
docs: Open a file, downloading it first if it does not yet exist.
  
          Unlike when you call a loader directly like ``my_loader()``,
          this ``my_loader.open()`` method does not attempt to parse or
          interpret the file; it simply returns an open file object.
  
          The ``url`` can be either an external URL, or else the path to a
          file on the current filesystem.  A relative path will be assumed
          to be relative to the base directory of this loader object.
  
          If a URL was provided and the ``reload`` parameter is true, then
          any existing file will be removed before the download starts.
  
          The ``filename`` parameter lets you specify an alternative local
          filename instead of having the filename extracted from the final
          component of the URL.