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<H2><A NAME="SECTION004320000000000000000"></A><A NAME="id-classes"></A>
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2.3.2 Reserved classes of identifiers
</H2>

<P>
Certain classes of identifiers (besides keywords) have special
meanings.  These classes are identified by the patterns of leading and
trailing underscore characters:

<P>
<DL>
<DT><STRONG><code>_*</code></STRONG></DT>
<DD>Not imported by "<tt class="samp">from <var>module</var> import *</tt>".  The special
  identifier "<tt class="samp">_</tt>" is used in the interactive interpreter to store
  the result of the last evaluation; it is stored in the
  <tt class="module">__builtin__</tt> module.  When not in interactive mode, "<tt class="samp">_</tt>"  has no special meaning and is not defined.
  See section&nbsp;<A href="import.html#import">6.12</A>, ``The <tt class="keyword">import</tt> statement.''

<P>
<span class="note"><b class="label">Note:</b>
The name "<tt class="samp">_</tt>" is often used in conjunction with
  internationalization; refer to the documentation for the
  <a class="ulink" href="../lib/module-gettext.html"
  ><tt class="module">gettext</tt> module</a> for more
  information on this convention.</span>

<P>
</DD>
<DT><STRONG><code>__*__</code></STRONG></DT>
<DD>System-defined names.  These names are defined by the interpreter
  and its implementation (including the standard library);
  applications should not expect to define additional names using this
  convention.  The set of names of this class defined by Python may be
  extended in future versions.
  See section&nbsp;<A href="specialnames.html#specialnames">3.3</A>, ``Special method names.''

<P>
</DD>
<DT><STRONG><code>__*</code></STRONG></DT>
<DD>Class-private names.  Names in this category, when used within the
  context of a class definition, are re-written to use a mangled form
  to help avoid name clashes between ``private'' attributes of base
  and derived classes.
  See section&nbsp;<A href="atom-identifiers.html#atom-identifiers">5.2.1</A>, ``Identifiers (Names).''

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</DD>
</DL>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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