code: public static <E> double skewDivergence(Counter<E> c1, Counter<E> c2, double skew) {
      Counter<E> average = linearCombination(c2, skew, c1, (1.0 - skew));
      return klDivergence(c1, average);
    }
docs: Calculates the skew divergence between the two counters. That is, it
  calculates KL(c1 || (c2*skew + c1*(1-skew))) . In other words, how well can
  c1 be represented by a "smoothed" c2.
  
  @return The skew divergence between the distributions