2.3.2 Reserved classes of identifiers

Certain classes of identifiers (besides keywords) have special meanings. These are:

Form	Meaning	Notes
_*	Not imported by "from module import *"	(1)
__*__	System-defined name
__*	Class-private name mangling

(XXX need section references here.)

Note:

(1)

The special identifier "_" is used in the interactive interpreter to store the result of the last evaluation; it is stored in the __builtin__ module. When not in interactive mode, "_" has no special meaning and is not defined.