Spotipy - Cannot log in to authenticate (Authorization Code Flow) - python-3.x

Question

I am working with the Spotipy Python library to connect to the Spotify web API. I want to get access to my Spotify's user account via Authorization Code Flow. I am using Python 3.5, Spotipy 2.4.4, Google Chrome 55.0.2883.95 (64-bit) and Mac OS Sierra 10.12.2
First, I went to the Spotify Developer website to register the program to get a Client ID, a Client Secret key and enter a redirect URI (https://www.google.com) on my white-list.
Second, I set the environment variables from terminal:
export SPOTIPY_CLIENT_ID='my_spotify_client_id'
export SPOTIPY_CLIENT_SECRET='my_spotify_client_secret'
export SPOTIPY_REDIRECT_URI='https://www.google.com'
Then I try to run the example code typing 'python3.5 script.py my_username' from terminal. Here is the script:
import sys
import spotipy
import spotipy.util as util
scope = 'user-library-read'
if len(sys.argv) > 1:
username = sys.argv[1]
else:
print "Usage: %s username" % (sys.argv[0],)
sys.exit()
token = util.prompt_for_user_token(username, scope)
if token:
sp = spotipy.Spotify(auth=token)
results = sp.current_user_saved_tracks()
for item in results['items']:
track = item['track']
print track['name'] + ' - ' + track['artists'][0]['name']
else:
print "Can't get token for", username
When running this code, it takes me to a log in screen on my browser. I enter my Spotify's credential to grant access to my app. But when I finally click on 'log in' (or 'Iniciar sesión' in Spanish) nothing happens. I tried to log in with my Facebook account but it does not work either. It seems that I get a Bad Request every time that I click on 'log in'. Here is a capture of Chrome:
The process is incomplete because when trying to enter the redirect URI back on terminal I get another Bad Request:
raise SpotifyOauthError(response.reason)
spotipy.oauth2.SpotifyOauthError: Bad Request
I tried to restart my computer, clean my browser cookies, use another different browser but did not work. It seems that I am not the only one having this problem. Is it maybe a bug? Please, avoid answers like "read the documentation of the API going here". Thank you.

Answer 1

Solved it. In order to run the Authorization Code Flow example code provided in the Spotipy's documentation correctly, I specified the redirect URI in line 13 of the example script when calling util.prompt_for_user_token, even when I had done this previously when setting environment variables:
token = util.prompt_for_user_token(username, scope, redirect_uri = 'https://example.com/callback/')
Likewise, do not use https://www.google.com or similar web address as your redirect URI. Instead, try 'https://example.com/callback/' or 'http://localhost/' as suggested here. Do not forget that the redirected URL once you are logged in must have the word code included.
Cheers,