code: def download_to_stream(self, file_id, destination):
          
          gout = self.open_download_stream(file_id)
          for chunk in gout:
              destination.write(chunk)
docs: Downloads the contents of the stored file specified by file_id and
          writes the contents to `destination`.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # Get _id of file to read
            file_id = fs.upload_from_stream("test_file", "data I want to store!")
            # Get file to write to
            file = open('myfile','wb+')
            fs.download_to_stream(file_id, file)
            file.seek(0)
            contents = file.read()
  
          Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists.
  
          :Parameters:
            - `file_id`: The _id of the file to be downloaded.
            - `destination`: a file-like object implementing :meth:`write`.