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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def open_download_stream(self, file_id):
 """Opens a Stream from which the application can read the contents of the stored file specified by file_id. 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!") grid_out = fs.open_download_stream(file_id) contents = grid_out.read() Returns an instance of :class:`~gridfs.grid_file.GridOut`. Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists. :Parameters: - `file_id`: The _id of the file to be downloaded. """

        gout = GridOut(self._collection, file_id)

        # Raise NoFile now, instead of on first attribute access.
        gout._ensure_file()
        return gout