You will have to set PATH environment variable to set gekoriver.
Download gekodriver from here: https://github.com/mozilla/geckodriver/releases
You have to append the path to the directory containing gekodriver binary to your PATH environment variable value string.
In Unix based system,
export PATH = $PATH:/path/to/directory/of/gekodriver/executable/
in windows based system,
setx path "%path%;c:\path\to\gekodriver\dir"
And, in webdriver.Firefox construction, do not pass anything. Provided that your Firefox is installed at the default location.
So, your code should look like below.
//gecko = os.path.normpath(os.path.join(os.path.dirname(__file__), 'geckodriver'))
//self.driver = webdriver.Firefox(executable_path=gecko+'.exe')
self.driver = webdriver.Firefox()