code: static public Probability or(Probability probability1, Probability probability2) {
          double p1 = probability1.value;
          double p2 = probability2.value;
          return new Probability(p1 + p2 - (p1 * p2));
      }
docs: This function returns the logical disjunction of the specified probabilities.  The value
  of the logical disjunction of two probabilities is P + Q - and(P, Q).
  
  @param probability1 The first probability.
  @param probability2 The second probability.
  @return The logical disjunction of the two probabilities.