def negation
      if @entry.at_xpath('./cda:act[@actionNegationInd="true"]')
        is_negation_rationale = (comparison.restrictions.map {|restriction| restriction.type }).include? 'RSON' if comparison
        if is_negation_rationale
          false
        else
          true
        end
      else
        false
      end
    end
def negation
      if @entry.at_xpath('./cda:act[@actionNegationInd="true"]')
        is_negation_rationale = (comparison.restrictions.map {|restriction| restriction.type }).include? 'RSON' if comparison
        if is_negation_rationale
          false
        else
          true
        end
      else
        false
      end
    end
Return whether the precondition is negated (true) or not (false)