def METHOD_NAME(self):
    """
    Set up any connections required by the handler
    Should return output of check_connection() method after attempting
    connection. Should switch self.is_connected.
    Returns:
        HandlerStatusResponse
    """
    if self.is_connected is True:
        return self.service
    if self.credentials_file:
        if os.path.exists('token_books.json'):
            self.credentials = Credentials.from_authorized_user_file('token_books.json', self.scopes)
        if not self.credentials or not self.credentials.valid:
            if self.credentials and self.credentials.expired and self.credentials.refresh_token:
                self.credentials.refresh(Request())
            else:
                self.credentials = service_account.Credentials.from_service_account_file(
                    self.credentials_file, scopes=self.scopes)
        # Save the credentials for the next run
        with open('token_books.json', 'w') as token:
            token.write(self.credentials.to_json())
        self.service = build('books', 'v1', credentials=self.credentials)
    return self.service