docs: def _CheckAttribute(self, attribute, value):
      """Check that the value is of the expected type.
  
      Args:
         attribute: An instance of Attribute().
         value: An instance of RDFValue.
  
      Raises:
         ValueError: when the value is not of the expected type.
         AttributeError: When the attribute is not of type Attribute().
      """
      if not isinstance(attribute, Attribute):
        raise AttributeError("Attribute %s must be of type aff4.Attribute()" %
                             attribute)
  
      if not isinstance(value, attribute.attribute_type):
        raise ValueError("Value for attribute %s must be of type %s()" %
                         (attribute, attribute.attribute_type.__name__))