perly guarded.
See if you can construct a text file which causes the program to fail
and then modify the program so that the line is properly guarded and 
test it to make sure it handles your new text file.
</em></font></div><br />
<div align="left"><font color="black"><b>Exercise&nbsp;3</b>&nbsp;&nbsp;<em>
Rewrite the guardian code in the above example without two
<tt>if</tt> statements. Instead use a compound logical expression using the
<tt>and</tt> logical operator with a single <tt>if</tt> statement.
<