title: Dropbox use of "ListFolderAsync" with a filter
body: <p>I would like to list the directories at the root of my Dropbox application.
  To do that I use the ListFolderAsync function of the Dropbox API and it works.</p>
  
  <p><strong><code>var list = await dbx.Files.ListFolderAsync ("");</code></strong></p>
  
  <p>Is it possible to add a filter to this function to retrieve only directories belonging to the filter?
  Something like all directories whose names begin with "ABCD"</p>
  
  <p>Thank you for your answers.
  YC</p>