'Renders default value of a given class.
Args:
value_cls: Default value of this class will be rendered. This class has
to be (or to be a subclass of) a self.value_class (i.e.
a class that this renderer is capable of rendering).
Returns:
An initialized default value.
Raises:
DefaultValueError: if something goes wrong.'

def BuildDefaultValue(self, value_cls):

    try:
        return value_cls()
    except Exception as e:
        logging.exception(e)
        raise DefaultValueError(("Can't    create    default    for    value    %s:    %s" % (value_cls.__name__, e)))
