title: Use of gather() in a loop, "key" and "value" as a variable
body: <p>I like to use <code>gather()</code> in loop, where values for the inputs of <code>gather()</code> <code>key</code> and <code>value</code> are a variable. Is this possible?</p>
  <p>I also tried <code>gather()</code> with a standard variable (set outside the loop, without a index), but is doesn't work.</p>
  <p>So, I assume, that it is not possible per definition of _gather()_to assign <code>key</code> and <code>value</code> to a variable.</p>
  <p>In the documentation I found on <strong>key</strong> and <strong>value</strong>:</p>
  <p>&quot;...note that this kind of interface where symbols do not represent actual objects...&quot;</p>
  <p>I assume that's the answer.
  But I'm not sure.</p>
  <pre><code>gather(Fragenummern.FB[i], Fragenummern.FI[i], 
         key = keyVar[i], value = ValueVar[i])  
  </code></pre>
  <blockquote>
  <p>Error: Must supply a symbol or a string as argument</p>
  <p>Call <code>rlang::last_error()</code> to see a backtrace</p>
  </blockquote>