title: elastic search. using scroll method to read large dataset but "scan" as search type is not working
body: <p>First two lines of the code works. When I set search_type as "scan", it says "Error: 400 - No search type for [scan]" </p>
  
  <pre><code>Search('shakespeare', q="a*")$hits$total
  #&gt; [1] 2747
  res &lt;- Search(index = 'shakespeare', q="a*", scroll="1m")
  res &lt;- Search(index = 'shakespeare', q="a*", scroll="1m", search_type = "scan")
  </code></pre>
  
  <p>What can I do to make this work?</p>