Request a list of games owned by a given steam id.

        steamID: The users id
        include_appinfo: boolean.
        include_played_free_games: boolean.
        appids_filter: a json encoded list of app ids.
        format: Return format. None defaults to json. (json, xml, vdf)

def get_owned_games(self, steamID, include_appinfo=1,
            include_played_free_games=0, appids_filter=None, format=None):
        """Request a list of games owned by a given steam id.

        steamID: The users id
        include_appinfo: boolean.
        include_played_free_games: boolean.
        appids_filter: a json encoded list of app ids.
        format: Return format. None defaults to json. (json, xml, vdf)

        """
        parameters = {
                    'steamid' : steamID,
                    'include_appinfo' : include_appinfo,
                    'include_played_free_games' : include_played_free_games
                    }
        if format is not None:
            parameters['format'] = format
        if appids_filter is not None:
            parameters['appids_filter'] = appids_filter
        url = self.create_request_url(self.interface, 'GetOwnedGames', 1,
            parameters)
        data = self.retrieve_request(url)
        return self.return_data(data, format=format)