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<H1><A NAME="SECTION0071200000000000000000"></A><A NAME="exprlists"></A>
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5.12 Expression lists
</H1>
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<P>
<dl><dd class="grammar">
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<table>
<tr>
    <td><a id='tok-expression_list' xml:id='tok-expression_list'>expression_list</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="Booleans.html#tok-expression">expression</a> ( "," <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> )* [","]</td></tr>
</table>
</div>
<a class="grammar-footer"
  href="grammar.txt" type="text/plain"
  >Download entire grammar as text.</a>
</dd></dl>

<P>
An expression list containing at least one comma yields a
tuple.  The length of the tuple is the number of expressions in the
list.  The expressions are evaluated from left to right.
<a id='l2h-447' xml:id='l2h-447'></a>
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The trailing comma is required only to create a single tuple (a.k.a. a
<em>singleton</em>); it is optional in all other cases.  A single
expression without a trailing comma doesn't create a
tuple, but rather yields the value of that expression.
(To create an empty tuple, use an empty pair of parentheses:
<code>()</code>.)
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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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