<span class='va'>x</span><span class='op'>)</span>
 <span class='co'>## this is a data.frame of assertions, their description and column names</span>

 <span class='co'>## list the descriptions of all (current) assertions</span>
 <span class='va'>asserts</span><span class='op'>$</span><span class='va'>description</span>

 <span class='co'>## assertion columns from data</span>
 <span class='va'>tmp</span> <span class='op'>&lt;-</span> <span class='va'>x</span><span class='op'>$</span><span class='va'>data</s