 'c']
</font></pre><font color="black">The parameter <tt>t</tt> and the variable <tt>letters</tt> are
aliases for the same object. <br />
<br />
It is important to distinguish between operations that
modify lists and operations that create new lists. For
example, the <tt>append</tt> method modifies a list, but the
<tt>+</tt> operator creates a new list:</font><br />
<br />
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<pre><font size="4" color="b