code: private LinkedHashSet<Formula> condenseOperandsAnd(final Collection<? extends Formula> operands) {
      final LinkedHashSet<Formula> ops = new LinkedHashSet<>();
      this.cnfCheck = true;
      for (final Formula form : operands)
        if (form.type() == AND) {
          for (final Formula f : ((NAryOperator) form).operands) {
            this.addFormulaAnd(ops, f);
            if (!this.formulaAdditionResult[0])
              return null;
            if (!this.formulaAdditionResult[1])
              this.cnfCheck = false;
          }
        } else {
          this.addFormulaAnd(ops, form);
          if (!this.formulaAdditionResult[0])
            return null;
          if (!this.formulaAdditionResult[1])
            this.cnfCheck = false;
        }
      return ops;
    }
docs: Returns a condensed array of operands for a given n-ary conjunction.
  @param operands the formulas
  @return a condensed array of operands