title: Fatest way to check and create folder in document library within SharePoint Online (CSOM)?
body: <p>I have a SharePoint Online where I can connect through my console application successfully:</p>
  
  <pre><code>private static ClientContext GetUserContext()
  {
     var o365SecurePassword = new SecureString();
  
     foreach (char c in o365Password)
     {
         o365SecurePassword.AppendChar(c);
     }
  
     var o365Credentials = new SharePointOnlineCredentials(o365Username, o365SecurePassword);
  
     var o365Context = new ClientContext(o365SiteUrl);
     o365Context.Credentials = o365Credentials;
  
     return o365Context;
  }
  </code></pre>
  
  <p>But what I need now to do is to go into my SharePoint Document Library named "doc_archive" and check if there exists a folder with name "K20170409-01". 
  If not create a new one.</p>
  
  <p><strong>Failed Attempt</strong></p>
  
  <pre><code>ClientContext context = GetUserContext();
  
  Web web = context.Web;
  Web webroot = context.Site.RootWeb;
  context.Load(web);
  context.Load(webroot);
  
  List list = webroot.GetList("doc_archive");
  context.Load(list);
  
  FolderCollection folders = list.RootFolder.Folders;
  context.Load(folders);
  
  IEnumerable&lt;Folder&gt; existingFolders = context.LoadQuery(
      folders.Include(
      folder =&gt; folder.Name)
  );
  context.ExecuteQuery();
  </code></pre>
  
  <p>What is the fastest ways to check and create a folder within a document library in SharePoint Online via CSOM (commandline application)?</p>