code: public final static <T extends Comparable<? super T>> Observable<T> min(Observable<T> source) {
          return OperatorMinMax.min(source);
      }
docs: Returns an Observable that emits the single numerically minimum item emitted by the source Observable.
  If there is more than one such item, it returns the last-emitted one.
  <p>
  <img width="640" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/min.png" alt="">
  
  @param source
  an Observable to determine the minimum item of
  @return an Observable that emits the minimum item emitted by the source Observable
  @throws IllegalArgumentException
  if the source is empty
  @see <a href="http://msdn.microsoft.com/en-us/library/hh229715.aspx">MSDN: Observable.Min</a>