def add(self, attr):
    assert (self.name in [None, attr.name])
    self.name = attr.name
    value = helper.get_attribute_value(attr)
    if isinstance(value, list):
        value = tuple(value)
    self.values.add(str(value))
def add(self, attr):
    assert (self.name in [None, attr.name])
    self.name = attr.name
    value = helper.get_attribute_value(attr)
    if isinstance(value, list):
        value = tuple(value)
    self.values.add(str(value))