def conjunction_code
      case @type
      when HQMF::PopulationCriteria::IPP, HQMF::PopulationCriteria::DENOM, HQMF::PopulationCriteria::NUMER,
           HQMF::PopulationCriteria::MSRPOPL, HQMF::PopulationCriteria::STRAT
        HQMF::Precondition::ALL_TRUE
      when HQMF::PopulationCriteria::DENEXCEP, HQMF::PopulationCriteria::DENEX, HQMF::PopulationCriteria::MSRPOPLEX,
           HQMF::PopulationCriteria::NUMEX
        HQMF::Precondition::AT_LEAST_ONE_TRUE
      else
        fail "Unknown population type [#{@type}]"
      end
    end
def conjunction_code
      case @type
      when HQMF::PopulationCriteria::IPP, HQMF::PopulationCriteria::DENOM, HQMF::PopulationCriteria::NUMER,
           HQMF::PopulationCriteria::MSRPOPL, HQMF::PopulationCriteria::STRAT
        HQMF::Precondition::ALL_TRUE
      when HQMF::PopulationCriteria::DENEXCEP, HQMF::PopulationCriteria::DENEX, HQMF::PopulationCriteria::MSRPOPLEX,
           HQMF::PopulationCriteria::NUMEX
        HQMF::Precondition::AT_LEAST_ONE_TRUE
      else
        fail "Unknown population type [#{@type}]"
      end
    end
Get the conjunction code, ALL_TRUE or AT_LEAST_ONE_TRUE
 @return [String] conjunction code