title: Transmutation Does not Apply to Each Row
body: <p>I am working with the tidyverse and rvest.</p>
  
  <p>I've created a tibble with a single column; a series of strings that include HTML markdown.  I'm attempting to go through each one and filter out the markdown from the strings.  This seems to be the correct usage of Transmute and the rvest read_html/html_text: </p>
  
  <pre><code>transmute(responses, response_stripped = html_text(read_html(response_content)))
  </code></pre>
  
  <p>And it's true that it beautifully filters the first row.  However, it then takes that result and repeats it for every row following rather than processing them individually.</p>
  
  <pre><code>   response_stripped                                                                   
     &lt;chr&gt;                                                                               
   1 The only real branch points that lead me to the right diagnosis occurred after disc…
   2 The only real branch points that lead me to the right diagnosis occurred after disc…
   3 The only real branch points that lead me to the right diagnosis occurred after disc…
  </code></pre>
  
  <p>Any idea why this is happening?</p>