code: def email(self):
          
          if not self.credentials:
              return None
          try:
              return self.credentials.id_token['email']
          except KeyError:
              current_app.logger.error(
                  'Invalid id_token {0}'.format(self.credentials.id_token))
docs: Returns the user's email address or None if there are no credentials.
  
          The email address is provided by the current credentials' id_token.
          This should not be used as unique identifier as the user can change
          their email. If you need a unique identifier, use user_id.