The implementation adds a few special read-only attributes to several object types, where they are relevant:
x.__dict__
is a dictionary of some sort used to store an
object's (writable) attributes;x.__methods__
lists the methods of many built-in object types,
e.g., [].__methods__
yields
['append', 'count', 'index', 'insert', 'remove', 'reverse', 'sort']
;x.__members__
lists data attributes;x.__class__
is the class to which a class instance belongs;x.__bases__
is the tuple of base classes of a class object.