[scikit-learn] partial_fit implementation for IsolationForest

hello scikit-learn devs, After following the work on IsolationForest so far and testing on a real-world problem here we've found this model to be very promising for anomaly detection. However, at present, IsolationForest only fits data in batch even while it may be well suited to incremental on-line learning since one could subsample recent history and older estimators can be dropped progressively. I'd like to contribute this feature, but being new to ML and scikit-learn I'm curious how I should start making a quick & dirty version to see how this may work. Are there other good examples where one could see the difference between .fit and .partial_fit in other models? thanks isaak y.