&gt;</span> <span style="color: #BCBCBC;">1</span> a         1     1        4</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> <span style="color: #BCBCBC;">2</span> a         2     2        5</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> <span style="color: #BCBCBC;">3</span> a         3     3        6</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> <span style="color: #BCBCBC;">4</span> b         1     1        7</span>
<span class="r-out co"><span class="r-pr">#