text: from google_auth_oauthlib.flow import InstalledAppFlow
  from google.auth.transport.requests import Request
  from google.oauth2.credentials import Credentials
  from os.path import exists
  
  # If modifying these scopes, delete the file token.json.
  SCOPES = ['https://www.googleapis.com/auth/drive.readonly', 'https://www.googleapis.com/auth/spreadsheets.readonly']
  
  
  def get_credentials():
      credentials = None
      # The file token.json stores the user's access and refresh tokens, and is
      # created automatically when the authorization flow completes for the first
      # time.
      if exists('token.json'):
          credentials = Credentials.from_authorized_user_file('token.json', SCOPES)
  
      # If there are no (valid) credentials available, let the user log in.
      if not credentials or not credentials.valid:
          if credentials and credentials.expired and credentials.refresh_token:
              credentials.refresh(Request())
          else:
              flow = InstalledAppFlow.from_client_secrets_file(
                  'credentials.json', SCOPES)
              credentials = flow.run_local_server(port=0)
          # Save the credentials for the next run
          with open('token.json', 'w') as token:
              token.write(credentials.to_json())
  
      return credentials
  