ck">Because <tt>sort</tt> returns <tt>None</tt>, the
next operation you perform with <tt>t</tt> is likely to fail.<br />
<br />
Before using list methods and operators, you should read the
documentation carefully and then test them in interactive mode. The
methods and operators that lists share with other sequences (like
strings) are documented at
<tt>docs.python.org/lib/typesseq.html</tt>. The
methods and operators that only apply to mutable sequences
are documented at <tt>docs.python.org/lib/typesseq-muta