def getCliInstance():
	global _dbcli
	if not _dbcli:
		_dbcli = DatabaseHelper()
	return _dbcli
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))