guava/src/com/google/common/collect/TopKSelector.java
public static <T extends Comparable<? super T>> TopKSelector<T> least(int k) {
    return least(k, Ordering.natural());
  }
public static <T extends Comparable<? super T>> TopKSelector<T> least(int k) {
    return least(k, Ordering.natural());
  }
Returns a {@code TopKSelector} that collects the lowest {@code k} elements added to it,
relative to the natural ordering of the elements, and returns them via {@link #topK} in
ascending order.

@throws IllegalArgumentException if {@code k < 0}