code: public FormulaFactoryStatistics statistics() {
      final FormulaFactoryStatistics statistics = new FormulaFactoryStatistics();
      statistics.name = this.name;
      statistics.positiveLiterals = this.posLiterals.size();
      statistics.negativeLiterals = this.negLiterals.size();
      statistics.negations = this.nots.size();
      statistics.implications = this.implications.size();
      statistics.equivalences = this.equivalences.size();
      statistics.conjunctions2 = this.ands2.size();
      statistics.conjunctions3 = this.ands3.size();
      statistics.conjunctions4 = this.ands4.size();
      statistics.conjunctionsN = this.andsN.size();
      statistics.disjunctions2 = this.ors2.size();
      statistics.disjunctions3 = this.ors3.size();
      statistics.disjunctions4 = this.ors4.size();
      statistics.disjunctionsN = this.orsN.size();
      statistics.pbcs = this.pbConstraints.size();
      statistics.ccCounter = this.ccCounter;
      statistics.pbCounter = this.pbCounter;
      statistics.cnfCounter = this.cnfCounter;
      return statistics;
    }
docs: Returns the statistics for this formula factory.
  @return the statistics for this formula factory