Thief().pickpocket()

An instance of a class is created when the class is called with an assignment (i.e., kenneth = Thief() ). The method can then be called on that instance as: Thief.pickpocket(kenneth). Similarly, Thief().pickpocket() is valid, but generates a different instance object (and can change from call to call) when openly called this way without a specific instance. You can check for object equivalency with the id( ) function. When you run this, the specific object id's will be different on your system, but their consistency with respect to each other will remain:

>>> kenneth = Thief()
>>> id(kenneth)            # always returns 49494280
49494280
>>> id(Thief())              # object id varies (may need to run several times to see different values)
49926944
>>> id(Thief())
49850464

To see this instance object creation more clearly, I've added the simple init method which allows us to give the Thief a name attribute when created:

import random

class Thief:
    sneaky = True

    def __init__(self, name):
        self.name = name

    def pickpocket(self):
        if self.sneaky:
            return bool(random.randint(0, 1))
        return False

Now, Kenneth didn't mention this because he was trying to keep the exercise simple, but it is always a good idea to provide some kind of initialization requirement for your class objects. When you run the above code, you will see a TypeError if you try :

>>> mark = Thief()

because now init requires that any new instance be created with a positional argument: 'name'. So, in turn, you will see you can no longer run: Thief().pickpocket() An instance is now created for example as:

>>> mark = Thief('Mark')

Note: The instance mark created above will always point to the same object, however, repeating the assignment by calling Thief again will produce a different object.

In summary, each time you call the class (i.e., kenneth = Thief( ), Thief( ).pickpocket( ), Thief('Mark').pickpocket( ) ) a new object is created. When you only use the method (i.e., kenneth.pickpocket( ), Thief.pickpocket(mark) ) on a specific instance that already exists, no new object is created and the method operates on that specific instance object.