Python google gmail api basic oauth2 authorization

gmail-simple-oauth2.py

from googleapiclient.discovery import build
from oauth2client import file, client, tools

SCOPES = ['https://www.googleapis.com/auth/gmail.readonly']

# To get credentials.json see https://developers.google.com/gmail/api/quickstart/python
def get_credentials():
    storage = file.Storage('storage.json')
    credentials = storage.get()
    if credentials is None or credentials.invalid:
        flow = client.flow_from_clientsecrets('credentials.json', SCOPES)
        credentials = tools.run_flow(flow, storage)
    return credentials
    
    
def get_labels():
    service = build('gmail', 'v1', credentials=get_credentials())
    results = service.users().labels().list(userId='me').execute()
    return results.get('labels', [])