How to check Progrmatically if list or document library exists in SharePoint client object model ?

string siteUserName="nam",_siteurl="http://sharepoint.com",_sitepassword ="pass@word1"; 

ClientContext clientContext = new ClientContext(_siteurl);
 clientContext.AuthenticationMode =ClientAuthenticationMode.Default;
 clientContext.Credentials = new System.Net.NetworkCredential(_siteUserName, _sitepassword, _domainName);  Web oweb = clientContext.Web;
SharePointclientObj.ListCollection lists = oweb.Lists;
 clientContext.Load(lists);
                        clientContext.ExecuteQuery();
                        var existingLists = clientContext.LoadQuery(lists.Where(list => list.Title == listname));

                        clientContext.ExecuteQuery();
                       var existingList = existingLists.FirstOrDefault();
                       if (existingList == null)
                       {
 SharePointclientObj.ListCreationInformation lci = new SharePointclientObj.ListCreationInformation();
                           lci.Description ="Test";
                           lci.Title = "Test";
                           lci.TemplateType = 101;
                           SharePointclientObj.List newLib = clientContext.Web.Lists.Add(lci);
                           clientContext.Load(newLib);

                           clientContext.ExecuteQuery();


}