def text(self):
        """Get indent text as \t or string of spaces
        """
        if self.useTabs:
            return '\t'
        else:
            return ' ' * self.width
def test_supertype(self):
        self.assert_(isinstance(None, NullType))
        self.assert_(isinstance(Optional('a'), NullType))
        self.assert_(isinstance(NotPassed, NotPassedType))
        self.assert_(isinstance(NotPassed, NullType))