appengine.py 文件源码

def _validate(self, value):
      """Validates a value as a proper credentials object.

      Args:
        value: A value to be set on the property.

      Raises:
        TypeError if the value is not an instance of Credentials.
      """
      if value is not None and not isinstance(value, Credentials):
        raise TypeError('Property %s must be convertible to a credentials '
                        'instance; received: %s.' % (self._name, value))