r(*, "class")= chr "breathtest_data"</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ group_a:List of 23</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   ..- attr(*, "class")= chr "breathtest_data"</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ group_b:List of 23</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>   ..- attr(*, "class")= chr "breathtest_data"</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  $ group_b:List of 23</span>
