you need to have already initialized trakt api with store=True

trakt-to-google-calendar.py

from __future__ import print_function
import httplib2
import os

from apiclient import discovery
import oauth2client
from oauth2client import client
from oauth2client import tools

import datetime
from trakt.calendar import MyShowCalendar
try:
    import argparse
    flags = argparse.ArgumentParser(parents=[tools.argparser]).parse_args()
except ImportError:
    flags = None

SCOPES = 'https://www.googleapis.com/auth/calendar'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Google Calendar API Quickstart'
TIMEZONE = 'YOUR-OWN-TIMEZONE'

def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """
    home_dir = os.path.expanduser('~')
    credential_dir = os.path.join(home_dir, '.credentials')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir,
                                   'calendar-quickstart.json')

    store = oauth2client.file.Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = tools.run_flow(flow, store, flags)
        else: # Needed only for compatability with Python 2.6
            credentials = tools.run(flow, store)
        print('Storing credentials to ' + credential_path)
    return credentials

def main():
    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('calendar', 'v3', http=http)
    
    s_calendar = MyShowCalendar(days=30)

    for episode in s_calendar:
        episode_sting =  "{} S{}E{}".format(episode.show,episode.season,episode.number)
        start_date =  episode.airs_at
        end_date = start_date + datetime.timedelta(days=1)

        event = {
          'summary': episode_sting,
          'start': {
            'date': start_date.strftime('%Y-%m-%d'),
            'timeZone': TIMEZONE
          },
          'end': {
            'date': end_date.strftime('%Y-%m-%d'),
            'timeZone': TIMEZONE
            },
          'reminders': {
            'useDefault': False,
            'overrides': [
              {'method': 'popup', 'minutes': 12*60},
            ],
          },
        }

        event = service.events().insert(calendarId='primary', body=event).execute()
        print("Event created: {}".format(event.get('htmlLink')))
    print("done")

if __name__ == '__main__':
    main()