In Python, str is a class. And all classes act as function. If there is ever any doubt, you can tell like this: >>> type(str) <type 'type'> You can

In Python, str is a class. And all classes act as function. If there is ever any doubt, you can tell like this: >>> type(str) <type 'type'> You can tell that str is a class because it inherits from type type.