title: Xgboost crossvalidated model access
body: <p>Is there any way I can access the trained <code>xgboost</code> model from <code>xgboost.cv</code> directly? Or do I manually have to loop over the folds and perform a fit in this case?</p>
  
  <pre><code>xgb.cv(param, dtrain, num_round, nfold = 5, seed = 0,
         obj = logregobj, feval=evalerror)
  </code></pre>