https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='st'>"2015-06-30"</span>, <span class='st'>"2015-09-30"</span>, <span class='st'>"2015-12-30"</span>, 
                             <span class='st'>"2015-06-30"</span>, <span class='st'>"2015-09-30"</span>, <span class='st'>"2015-12-30"</span><span class='op'>)</span>,
                 QSCAT   <span class='op'>=</span> <span class='st'>"A"</span>,
                 QSORRES <span class='op'>=</span>  <span class='va'>LETTERS</spa