<!DOCTYPE html PUBLIC
"-//W3C//DTD HTML 4.0 Transitional//EN">
<link rel=
"STYLESHEET" href=
"lib.css" type='text/css'
/>
<link rel=
"SHORTCUT ICON" href=
"../icons/pyfav.png" type=
"image/png" />
<link rel='start' href='../index.html' title='Python Documentation Index'
/>
<link rel=
"first" href=
"lib.html" title='Python Library Reference'
/>
<link rel='contents' href='contents.html'
title=
"Contents" />
<link rel='index' href='genindex.html' title='Index'
/>
<link rel='last' href='about.html' title='About this document...'
/>
<link rel='help' href='about.html' title='About this document...'
/>
<link rel=
"prev" href=
"module-exceptions.html" />
<link rel=
"parent" href=
"builtin.html" />
<link rel=
"next" href=
"python.html" />
<meta name='aesop' content='information'
/>
<title>2.5 Built-in Constants
</title>
<div id='top-navigation-panel' xml:id='top-navigation-panel'
>
<table align=
"center" width=
"100%" cellpadding=
"0" cellspacing=
"2">
<td class='online-navigation'
><a rel=
"prev" title=
"2.4 Built-in Exceptions"
href=
"module-exceptions.html"><img src='../icons/previous.png'
border='
0' height='
32' alt='Previous Page' width='
32'
/></A></td>
<td class='online-navigation'
><a rel=
"parent" title=
"2. Built-In Objects"
href=
"builtin.html"><img src='../icons/up.png'
border='
0' height='
32' alt='Up One Level' width='
32'
/></A></td>
<td class='online-navigation'
><a rel=
"next" title=
"3. Python Runtime Services"
href=
"python.html"><img src='../icons/next.png'
border='
0' height='
32' alt='Next Page' width='
32'
/></A></td>
<td align=
"center" width=
"100%">Python Library Reference
</td>
<td class='online-navigation'
><a rel=
"contents" title=
"Table of Contents"
href=
"contents.html"><img src='../icons/contents.png'
border='
0' height='
32' alt='Contents' width='
32'
/></A></td>
<td class='online-navigation'
><a href=
"modindex.html" title=
"Module Index"><img src='../icons/modules.png'
border='
0' height='
32' alt='Module Index' width='
32'
/></a></td>
<td class='online-navigation'
><a rel=
"index" title=
"Index"
href=
"genindex.html"><img src='../icons/index.png'
border='
0' height='
32' alt='Index' width='
32'
/></A></td>
<div class='online-navigation'
>
<b class=
"navlabel">Previous:
</b>
<a class=
"sectref" rel=
"prev" href=
"module-exceptions.html">2.4 Built-in Exceptions
</A>
<b class=
"navlabel">Up:
</b>
<a class=
"sectref" rel=
"parent" href=
"builtin.html">2. Built-In Objects
</A>
<b class=
"navlabel">Next:
</b>
<a class=
"sectref" rel=
"next" href=
"python.html">3. Python Runtime Services
</A>
<!--End of Navigation Panel-->
<H1><A NAME=
"SECTION004500000000000000000">
2.5 Built-in Constants
</A>
A small number of constants live in the built-in namespace. They are:
<dl><dt><b><tt id='l2h-
323' xml:id='l2h-
323'
>False
</tt></b></dt>
The false value of the
<tt class=
"class">bool
</tt> type.
<span class=
"versionnote">New in version
2.3.
</span>
<dl><dt><b><tt id='l2h-
324' xml:id='l2h-
324'
>True
</tt></b></dt>
The true value of the
<tt class=
"class">bool
</tt> type.
<span class=
"versionnote">New in version
2.3.
</span>
<dl><dt><b><tt id='l2h-
325' xml:id='l2h-
325'
>None
</tt></b></dt>
The sole value of
<code><tt class=
"module"><a href=
"module-types.html">types
</a></tt>.NoneType
</code>.
<code>None
</code> is
frequently used to represent the absence of a value, as when default
arguments are not passed to a function.
<dl><dt><b><tt id='l2h-
326' xml:id='l2h-
326'
>NotImplemented
</tt></b></dt>
Special value which can be returned by the ``rich comparison''
special methods (
<tt class=
"method">__eq__()
</tt>,
<tt class=
"method">__lt__()
</tt>, and friends),
to indicate that the comparison is not implemented with respect to
<dl><dt><b><tt id='l2h-
327' xml:id='l2h-
327'
>Ellipsis
</tt></b></dt>
Special value used in conjunction with extended slicing syntax.
<div class='online-navigation'
>
<table align=
"center" width=
"100%" cellpadding=
"0" cellspacing=
"2">
<td class='online-navigation'
><a rel=
"prev" title=
"2.4 Built-in Exceptions"
href=
"module-exceptions.html"><img src='../icons/previous.png'
border='
0' height='
32' alt='Previous Page' width='
32'
/></A></td>
<td class='online-navigation'
><a rel=
"parent" title=
"2. Built-In Objects"
href=
"builtin.html"><img src='../icons/up.png'
border='
0' height='
32' alt='Up One Level' width='
32'
/></A></td>
<td class='online-navigation'
><a rel=
"next" title=
"3. Python Runtime Services"
href=
"python.html"><img src='../icons/next.png'
border='
0' height='
32' alt='Next Page' width='
32'
/></A></td>
<td align=
"center" width=
"100%">Python Library Reference
</td>
<td class='online-navigation'
><a rel=
"contents" title=
"Table of Contents"
href=
"contents.html"><img src='../icons/contents.png'
border='
0' height='
32' alt='Contents' width='
32'
/></A></td>
<td class='online-navigation'
><a href=
"modindex.html" title=
"Module Index"><img src='../icons/modules.png'
border='
0' height='
32' alt='Module Index' width='
32'
/></a></td>
<td class='online-navigation'
><a rel=
"index" title=
"Index"
href=
"genindex.html"><img src='../icons/index.png'
border='
0' height='
32' alt='Index' width='
32'
/></A></td>
<div class='online-navigation'
>
<b class=
"navlabel">Previous:
</b>
<a class=
"sectref" rel=
"prev" href=
"module-exceptions.html">2.4 Built-in Exceptions
</A>
<b class=
"navlabel">Up:
</b>
<a class=
"sectref" rel=
"parent" href=
"builtin.html">2. Built-In Objects
</A>
<b class=
"navlabel">Next:
</b>
<a class=
"sectref" rel=
"next" href=
"python.html">3. Python Runtime Services
</A>
<span class=
"release-info">Release
2.4.2, documentation updated on
28 September
2005.
</span>
<!--End of Navigation Panel-->
See
<i><a href=
"about.html">About this document...
</a></i> for information on suggesting changes.