def handle_base_populations(population_def, population)
      {
        HQMF::PopulationCriteria::IPP => 'initialPopulationCriteria',
        HQMF::PopulationCriteria::DENOM => 'denominatorCriteria',
        HQMF::PopulationCriteria::NUMER => 'numeratorCriteria',
        HQMF::PopulationCriteria::NUMEX => 'numeratorExclusionCriteria',
        HQMF::PopulationCriteria::DENEXCEP => 'denominatorExceptionCriteria',
        HQMF::PopulationCriteria::DENEX => 'denominatorExclusionCriteria',
        HQMF::PopulationCriteria::MSRPOPL => 'measurePopulationCriteria',
        HQMF::PopulationCriteria::MSRPOPLEX => 'measurePopulationExclusionCriteria'
      }.each_pair do |criteria_id, criteria_element_name|
        criteria_def = population_def.at_xpath("cda:component[cda:#{criteria_element_name}]", HQMF2::Document::NAMESPACES)
        if criteria_def
          build_population_criteria(criteria_def, criteria_id, population)
        end
      end
    end
def handle_base_populations(population_def, population)
      {
        HQMF::PopulationCriteria::IPP => 'initialPopulationCriteria',
        HQMF::PopulationCriteria::DENOM => 'denominatorCriteria',
        HQMF::PopulationCriteria::NUMER => 'numeratorCriteria',
        HQMF::PopulationCriteria::NUMEX => 'numeratorExclusionCriteria',
        HQMF::PopulationCriteria::DENEXCEP => 'denominatorExceptionCriteria',
        HQMF::PopulationCriteria::DENEX => 'denominatorExclusionCriteria',
        HQMF::PopulationCriteria::MSRPOPL => 'measurePopulationCriteria',
        HQMF::PopulationCriteria::MSRPOPLEX => 'measurePopulationExclusionCriteria'
      }.each_pair do |criteria_id, criteria_element_name|
        criteria_def = population_def.at_xpath("cda:component[cda:#{criteria_element_name}]", HQMF2::Document::NAMESPACES)
        if criteria_def
          build_population_criteria(criteria_def, criteria_id, population)
        end
      end
    end
Builds populations based an a predfined set of expected populations