There are two kinds of objects in Python:

<type 'type'> and <type 'object'> are two primitive objects of the system.

objectname.__class__ exists for every object and points the type of the object.

objectname.__bases__ exists for every type object and points the supertypes of the object. It is empty only for <type 'object'>.

To create a new object using subtyping, we use the class statement and specify the bases (and, optionally, the type) of the new object. This always creates a type object.

To create a new object using instantiation, we use the call operator (()) on the type object we want to use. This may create a type or a non-type object, depending on which type object was used.

Some non-type objects can be created using special Python syntax. For example, [1, 2, 3] creates an instance of <type 'list'>.

Internally, Python always uses a type object to create a new object. The new object created is an instance of the type object used. Python determines the type object from a class statement by looking at the bases specified, and finding their types.

issubtype(A,B) (testing for supertype-subtype relationship) returns True iff:

isinstance(A,B) (testing for type-instance relationship) returns True iff:

Squasher is really a python. (Okay, that wasn't mentioned before, but now you know.)