code: public Formula or(final Collection<? extends Formula> operands) {
      final LinkedHashSet<Formula> ops = new LinkedHashSet<>(operands);
      return this.constructOr(ops);
    }
docs: Creates a new disjunction from a collection of formulas.
  <p>
  Note: The LinkedHashSet is used to eliminate duplicate sub-formulas and to respect the commutativity of operands.
  @param operands the collection of formulas
  @return a new disjunction