python 3) instance, which will
        be encoded as `encoding` before being written. Any keyword arguments
        will be passed through to the created file - see
        :meth:`~gridfs.grid_file.GridIn` for possible arguments. Returns the
        ``"_id"`` of the created file.

        If the ``"_id"`` of the file is manually specified, it must
        not already exist in GridFS. Otherwise
        :class:`~gridfs.errors.FileExists` is raised.

        :Parameters:
          - `data`: data to be written as a file.
          - `**kwargs` (optional): keyword arguments for file creation

        .. versionchanged:: 3.0
           w=0 writes to GridFS are now prohibited.
        r$