 class='op'>=</span> <span class='va'>LETTERS</span><span class='op'>[</span><span class='fl'>1</span><span class='op'>:</span><span class='fl'>7</span><span class='op'>]</span>,</span>
<span class='r-in'>  x2 <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='st'>"B"</span>, <span class='st'>"C"</span>, <span class='st'>"D"</span>, <span class='st'>"E"</span>, <span class='st'>"C"</span>, <span class='st'>"A"</span>, <span cl