Python help

if operator != ("add"|"sub"):
    print ("Invalid Operator")

Basically I want to check if operator has anything other than "add" or "sub" assigned to it, but python 2.6 is saying

TypeError: unsupported operand type(s) for |: 'str' and 'str'

How should I check if operator is anything other than add or sub?

if not operator in ("add", "sub"):
    print ("Invalid Operator")

>>8
That parses to more tokens internally than the canonical
if operator not in ("add", "sub"):
    print("Invalid Operator")
Using the multi-word not in operator is more efficient^{[citation needed]} than an in operator being later negated by a not operator.