def handle_preconditions(id_generator)
      # Nest multiple preconditions under a single root precondition
      @preconditions = @entry.xpath('./*/cda:precondition[not(@nullFlavor)]', HQMF2::Document::NAMESPACES)
                       .collect do |pre|
        precondition = Precondition.parse(pre, @doc, id_generator)
        precondition.reference.nil? && precondition.preconditions.empty? ? nil : precondition
      end
      # Remove uneeded nils from the array
      @preconditions.compact!
    end
def handle_preconditions(id_generator)
      # Nest multiple preconditions under a single root precondition
      @preconditions = @entry.xpath('./*/cda:precondition[not(@nullFlavor)]', HQMF2::Document::NAMESPACES)
                       .collect do |pre|
        precondition = Precondition.parse(pre, @doc, id_generator)
        precondition.reference.nil? && precondition.preconditions.empty? ? nil : precondition
      end
      # Remove uneeded nils from the array
      @preconditions.compact!
    end
specifically handles extracting the preconditions for the population criteria