Name        : python-module-nulltype       Relocations: (not relocatable)
Version     : 2.2.5                             Vendor: ALT Linux Team
Release     : alt1                          Build Date: Thu Jan 12 05:36:44 2017
Install date: (not installed)               Build Host: igor.hasher.altlinux.org
Group       : Development/Python            Source RPM: (none)
Size        : 13177                            License: ASLv2.0
Packager    : Eugeny A. Rostovtsev (REAL) <real at altlinux.org>
URL         : https://pypi.python.org/pypi/nulltype
Summary     : Null values and sentinels like, but not, None
Description :
Helps define "null" values and sentinels parallel to, but different
from, None.

None is a great sentinel value and a classic implementation of the null
object pattern.

But there are times that you need more than one nullish value to
represent different aspects of emptiness. "Nothing there" is logically
different from "undefined," "prohibited," "end of data" and other kinds
of null.

The core function of nulltype is representing emptiness and falsity in a
way that doesn't overload None (or False, 0, {}, [], "", or any of the
other possible "there's nothing here!" values). It helps create
designated identifiers with specific meanings such as Passthrough,
Prohibited, and Undefined.