2, lexical analysis --3, keywords and identifiers

1 keyword

All reserved words

False      await      else       import     pass
None       break      except     in         raise
True       class      finally    is         return
and        continue   for        lambda     try
as         def        from       nonlocal   while
assert     del        global     not        with
async      elif       if         or         yield

2, to retain an identifier of the class

2.1 _*

It will not be from module import *imported

2.2 __*__

Name of the system definition.

These names are defined and implemented by an interpreter.

2.3 __*

The private name of the class.

When this name is used in the class definition, rewritten in a mixed form, in order to avoid name conflicts between "private" properties of the base class and a derived class.