def playlist_upload_cover_image(self, playlist_id, image_b64):
        """ Replace the image used to represent a specific playlist

            Parameters:
                - playlist_id - the id of the playlist
                - image_b64 - image data as a Base64 encoded JPEG image string
                    (maximum payload size is 256 KB)
        """
        plid = self._get_id("playlist", playlist_id)
        return self._put(
            f"playlists/{plid}/images",
            payload=image_b64,
            content_type="image/jpeg",
        )
 Replace the image used to represent a specific playlist

            Parameters:
                - playlist_id - the id of the playlist
                - image_b64 - image data as a Base64 encoded JPEG image string
                    (maximum payload size is 256 KB)
        
spotipy/client.py